Should I make the switch from 0W40 to 15W50

I know, I know, this has been discussed to death. I've read almost all the threads, but I still can't make up my mind. My Indy says they've had great luck with 15W50 , so he recommends getting it. My car has always had 0W40 from the dealer till now. The viscosity difference is about 21% at 100C (running conditions) but almost 56% at 40C (cold start). Keeping in mind the approaching warm weather ... 1) Should I make the switch? Has anyone else made the switch? Does the car feel any different ? (e.g. https://rennlist.com/forums/996-forum/292838-i-m-running-15w50-and.html ) 2) Will it cause any problems in the short term (i.e. suddenly changing the type of oil)? 3) Will it cause any problems in the long term (i.e. seizure, more wear and tear, etc)?

NO!!! Don't do it! Porsche does not approve it! It won't flow fast enough! Your engine will blow up! You will lose power! Your variocam will not work! It won't start because it is too thick! Your valves will lock up!, etc, etc, etc. All these reasons, plus dozens more will be given to you not to use, what I consider, is the proper oil for your engine in moderate and higher temps. Those who will attack you will not provide any evidence to their claims (maybe a link to a website or 2) and will not accept that a large percentage of these engines regularly run with the 15W50 with no problems whatsoever along with the added benefit of no lifter noise, less chance of leakage, better compression, less or no oil burning and smoother operation of the variocam. So, it is up to you. However, do not tell anyone that you make the change as you will be forever banned from talking about oil again on this forum. It is, however, a no brainer to NOT use 0W40.

1) I made the switch in my 01 at 75K miles, based on mechanic recommendation. Car was slightly smoother... otherwise no change. 2) No - many people run 15w50 3) Doubtful... would imagine though thie higher viscosity would prevent more leaks and may provide slightly better protection but #3 is purely opinion.

Did you see the Excellence article (last month I think) on oil? It's worth a read and I will stick with 0W40 after reading it.

Whatever you do, 1999, don't let any facts get in the way of your stellar advice!

There�s a fundamental flow in that article. It doesn�t mention anything about oil analyze. To recommend oil/oil change interval without some hard data from oil analyze is not convincing.

[Image-only post; no author-written text. Original image references:] https://rennlist.com/forums/images/smilies/popcorn.gif https://rennlist.com/forums/graemlins/drink.gif

Been waiting along time for some of these "facts" you keep mentioning? Having trouble finding some, are we?

No problem finding 'em...You have a problem accepting them...wether they are from me or anyone else...You should go back and read some of your own prior posts and some of the responses you generate from others...now that is truly worthy of a laugh! I think maybe you do it for entertainment value....

My indy mechanic also recommends 15W50 for all the Pcars he works on. I've not had any issues using it, no lifter noise complaints, and I had excellent results from a compression test. OH, and I have 80k+ miles and running... I did question him on his choice of 15W50 over 0W40, He said STFU, coz' he knows better than I do.....

C'mon 1999Porsche911 ... I've read your comments about a 100 times. I've read all the counter arguments, all the rebuttals and all the "hard facts". Who else has real experience with 15W50 (like rcg412 posted)? Thanks rcg412 & Cosmos, BTW.

Seriously, couldn't you have done a more extensive search on the forum a read the sideways-8 posts detailing everyone's opinion? It's like Talleyrand once quipped, "If we go on explaining we shall cease to understand one another."

Oh, yea! Here we go again. FWIW, I talked to a friend who is a mechanic at Newport Porsche here in SoCal and asked him what HE and his fellow mechanics feel about 0W40(as opposed to the corporate stance). He unequivocally stated that he feels it is the best oil. He's seen no problems with it and really does recommend it. He doesn't feel the old recommendations are bad, just that the newer viscosity is a better idea. I also had a nice talk about this with the owner of the independent shop I use, Hergesheimer Motorsports, and he agreed. He also uses 0W40 in his shop. He also said there is nothing wrong with the thicker oil, just that the lighter oil is better for these engines. So I use 0W40.

Sure would be great if we could get the 5W-50 here in the states.

Alright, real experience? I had 0W-40 and switched to 15W-50. I noticed nothing except the car seemed to get worse mileage. I'm switching back in the spring.

Dell, it'd be better if we could get OW-50; that way we would never have to discuss this ever again.

Want some HP with that Dell?

Here we go again....

Sorry, I'm a Mac guy. Ironic isn't it? Amen to that brother.

I've finally snapped! 1999, when you step up to the plate, and bear all fiscal responsibility for any engine related problems I might have as a result of following your advice that is contrary to the manufacture's, I'll use your recommendation. Until then, I wish you would just stop. I work all day handling service problems for a VERY large manufacturer of big yellow engines. We see your type all the time that think they have more knowledge than we have gained through development and testing of thousands of engines. End of rant. You are now returned to your regulalry scheduled programming.

What are we trying to get out of these discussions? Better performance, longer engine life or what? Had your Indy bad luck with 0W40 discoganya?

I am trying to elicit real experiences (and opinions) from people who have switched their oil. I specifically asked three questions in my first post. I don't want either. But I do want to avoid worse performance and shorter engine life No, my Indy has no evidence to support that.

So, you work for CAT? You probably work for a buddy of mine, who is in charge of the engine division. Recently moved over from Marine. I personally know half of your BOD and used to work for your compensation chairmen. Small world.

We don't need no stinkin' 0W40! The waterier (sp?) the better! I'm using 0W30 I'll let you know if my engine blows up

I am using 0W-40.....my car seems happy. JB

What common sence tells you about oil has very little to do with fact. Thinner oils dissapate heat better than thicker oil. Oil sheer which in itself creates heat and friction is reduced in thinner oils. With ultra fine high micron machined finishes, close bearing to shaft clearances and ultra thin piston rings, thicker and heavier oils used in the past few years are no longer needed nor perfered. Many Techs, independent or otherwise know very little about lubricants. Most have opinions based on incorrect information they have received over the years. The above are observations I have made about oils. I have studied them casually for years, talked with petrochemical engineers working for large motor oil manufacturers, I have built several successful roadracing motors and continue to build high performance motors with 5 in the works currently. I'm not trying to convince anyone to use any particular brand, type or weight of oil, swaying your religious and political persuasion is probably easier.

You can get Mobil 1 5w50 here in the states... We had this thread a couple months ago: https://rennlist.com/forums/showthre...&highlight=slr I found that some Mercedes dealers in the US may stock and can order Mobil 1 5w50 by the quart; the part number is Q1090134 ($7 per quart, the fill for the SLR).

Forgot to mention one thing... You can get close to 5w50 by mixing 0w40 and 15w50 at a one to one ratio. See https://rennlist.com/forums/showthre...&highlight=slr In the thread I indicated that I had spoken with some tech guys at Mobil headquarters [phone removed]), and they indicated that the 0w40 oil can be brought close to 5w50 levels by mixing 0w40 with 15w50 at about a 1 to 1 ratio. They also indicated that 5w40 Delvac won't be different than 0w40 for non-winter driving (driving in LA). Enough with the fussing and go enjoy a drive!

Amen Cy!

This is the most ridiculous debate ever. It makes the discussion of fuel quality look like metaphysics. There's no way to tell whether you are right or wrong about oil for, like, years. And only then if you have the equipment and skill to measure engine wear. The fact that your car seems "happy" or that you have had "no problems" is evidence of nothing. On that basis, I'd like to sell you a case of elephant repellent. I can personally vouch for the fact that not one pachyderm has darkened my door since the day I bought it. I also use it in the car now and, again, no elephants. As with most things on the internet, the passion in the argument is inversely proportional to the evidence available. I'm just going to stick with whatever it says in the manual. PM me if you want some of that elephant repellent. Willling to consider discounting for a group buy.

Bruce, don't forget that the TSB's on approved engine oils will supercede the manual. ps. add me to the group buy

And TSB's, yes. Just refilled my coffee cup. No elephants in the kitchen, either. This stuff rocks.

[Image-only post; no author-written text. Original image references:] https://rennlist.com/forums/graemlins/roflmao.gif

I use 20w50 because it says that I can in the manual, and I live in the humid Southeast. If the temperature will be below 50 degrees, then generally I don't drive the car. 1a) Only you can decide. 1b) Yes. 1c) Yes - variocam isn't usually as noticeable. 2) None that I've noticed. 3) None that I've noticed. FWIW, I used to run 20w50 in my Corvette C4 track car, and I never had problems even when the car was cold soaked from sitting all night in sub-freezing temps. So I don't sweat it if the car is cold... I'm just saying that if I lived up North I wouldn't use 20w50 in the winter. Michael

I run 0W-40 here in Central FL year round. That's what the dealership uses and what Mobil 1 recommends on their website. I only have ~21k miles on the engine, but no issues so far. This "thicker is better" argument is similar to a "more is better". On that note, I think I'll go put another hole in my head. More must be better...right. I wonder how my engine would run if I used the old grease out of the McDonalds fryers?

It is NOT "thicker is better" , but too thin is bad.

We are talking about oil right?

Oil???...Oh yeah, for some reason I had a McRib and Fries on my brain... I figured that was about as useful a contribution to this thread as some of the other expert comments.

I am also in the S.F. Bay Area, San Jose. With a 1997 Boxster that I bought 8 years ago. I confess - I use 15W-50. 61,000 miles. No engine problems. No leaks. I never switched to 15W-50. That is what has always been used. The local dealerships used it. Us local owners who do our own oil changes used it. When Porsche took it off the list a few years ago I continued to use it. When Mobil discontiuned the red top 15W-50 I started using the 15W-50 gold top EP. During the last oil change I also used an oil filter that Porsche does not use. It is your car. The choice is yours. http://www.renntech.org/forums/index.php?showtopic=9454

Update: I used 15W50 this time and drove about 400 miles this weekend and today. I noticed two changes: 1. The car idles smoother than before. Earlier the tachometer would sometimes jitter a little around 700 RPM; this does not happen anymore. 2. Cold start up noise is a little lesser. OK, it's been only 3 days since my oil change and I might be imagining some of this. I'll post a long term update (3-4 months) if I find something interesting. On the other hand, I'll be all too happy if I find nothing interesting

1999Porsche911 likes to throw his opinion around but here are what some Porsche experts have to say on this issue; The current issue of Excellence Magazine (April 2007) addresses aspects of the 0W-40 "oil" topic in a different manner. Both technical experts claim that newer Porsches require the thinner oil to ensure proper VarioCam function. On page 34 a reader asks a question about using 10W-40 oil (for a Boxster) in Florida vs Mobil 0W-40. He is concerned about using the 0W-40 because 10W-30 or 10W-40 is a "more common fill" in Florida (he also asks about break-in). The response from the Excellence technical expert was as follows. "Those who suggest higher viscosity oils usually don't understand the whole problem. Oil in engines is no longer just a lubricant. It is also a coolant for the engine as well as a hydralic control fluid for all of the things like VarioCam Plus, hydraulic lifters, and similar systems. If the oil is too high a viscosity, it can affect the way those circuits operate. The 2001 996 Turbo was the first Porsche to use the VarioCam Plus technology and a friend who works as a dealer technician told me that one of their technicians spend the whole day trying to diagnose a running problem caused by an owner who hadn't trusted Porsches factory fill and thus changed his oil to SAE 20W-50. The heavier oil totally confused the VarioCam plus system and the engine ran poorly. All of these devices have been designed to run with the SAE 0W-40 oils or other oils that Porsche recommends. Use only those oils recommended in your owners manual - SAE 0W-40, SAE 5W-40, or SAE 5W-50. Porsche is so sure about this decision that it came out with a bulletin recommending these oils for all of its older models as well." Now I know that is just one "experts" opinion. However, on page 169 Porsche tech expert Jim Pasha dedicates his entire "Tech Forum" article (6 pages worth) to "Oil". I'm not going to type in all 6 pages of material but I will quote a few short pieces of what Jim reports in his column (he covers a lot of ground in his article). "Why does Porsche specify such a low lower viscosity rating? The answer comes in two parts. First, in a quest for better fuel economy and longer engine life, Porsche engineers use bearing and cylinder-wall clearances far tighter than what they used previously. This creates less internal drag on components, and lighter oil is more compatible with tight tolerances." He also says; "In the latest Porsches, which use 0W-40, the thinner oil is critical to delicate systems that use motor oil as a hydralic activator. VarioCam Plus uses tiny "shafts" of oil created under high pressure to help the system alter valve timing. It is a trick system but it REQUIRES thin oil to work properly Finally here is what Porsche says on the matter; http://www.wrightune.co.uk/downloads/approved_oils.pdf To the best of my knowledge, 1999Porsche911 never responded to the thread in February when this information was originally published. I'd love to read his reasoning now. So, let's hear it 1999Porsche911. Why do the experts I listed above (plus Porsche's own engineers) have it all wrong??? Please tell me you have something better than it works fine in my car. Can't wait for the response!!

[Image-only post; no author-written text. Original image references:] http://www.discoweb.org/forums/images/smilies/lurk5.gif http://www.discoweb.org/forums/images/smilies/lurk5.gif http://www.discoweb.org/forums/images/smilies/lurk5.gif http://www.discoweb.org/forums/images/smilies/beer.gif http://www.discoweb.org/forums/images/smilies/beer.gif http://www.discoweb.org/forums/images/smilies/lurk5.gif http://www.discoweb.org/forums/images/smilies/lurk5.gif http://www.discoweb.org/forums/images/smilies/lurk5.gif

Sorry, but that article had nothing to do with the Variocam of the 00 engine as this thread does. Nice try, tho. Secondly, rather than living your life reading and following the opinions of others, why not actually do some testing. Then, whatever your position is, at least you have some data to back it up. I don't preach opinions of others, just my 35 years of experience. You did notice he stated that the engine was designed for 5W50 oil, didn't you? Or did you read over that part? And you are aware that a 15W50 oil at operating temperature is no different than a 5W50, don't you? So, please explain why a 15W50 is bad for the engine. is 5W50 is not. No one needs to follow anyone's opinion on thus forums, but they should have access to all the opinions to help make a judgement for themselves.

1999, as usual, shows that he lacks even the most basic understanding of oils and viscosity differences. One needs only to look at his posting history. Be careful before you follow any of the advice he gives on oils. When confronted with facts he will deny their worthiness and become defensive and claim no facts have ever been presented to him. Opinions and conjecture are worthless. Documented,real world testing and countless Used Oil Analysis reports, as well as the manufacturers updated recommendations should be enough to give the rational and intelligent owner reason enough to follow the TSB's on Porsches oil recommendations.

https://www.pca.org/tech/tech_qa_question.asp?id={D7EC45C3-9BA1-4C61-B220-8BA6874F1C20} check the following link for some more info on the subject...

Just what I thought you'd come up with, a version of "it works fine in my car". When you discussed you oil story in the past you never advised those with variocam plus not to follow your advice. It is very interesting that you are changing your tune now. I've never claimed to be any sort of oil expert. But, when the engineers that designed these motors recommend specific oils and those recommendations are reinforced by other independent experts, I think I'll stick with their advice. However, you imply in your post that you have done some "actual testing" on these motors and have "some data" to back up your position. Please do tell, I'd love to hear about the details of your testing.

I have been using 10W-40 as 2002 owner's manual specifies. Syntec has it and in "SL" form. just $0.02

Still waiting for your explaination as to why a 5W50 can be used and a 15W50 cannot. Please enlighten us as to what difference there is at operating temperture. I do NOT imply I have done testing, but I state clearly that I have done testing and plenty of it. Try doing so yourself for 35 years and maybe you can form an opinion on the subject rather that having someone else tell you what your opinion should be.

1999, you are clueless. Have you read one,single, piece of expert advice or do dismiss everyone who presents facts to you? My bet is you have done absolutely no meaningful testing at all. You have an opinion and not much else.

Seconds out - round two!

Running Vortech superchargers for many years, they recommended only 15W-50 Mobil 1 for the transmission of the S/C, 1999Porsche 911 is S/C'd somewhat justifying using the "thicker" oil. I am not taking sides but 5W-50 and 15W-50 is the same weight oil. The last number is the weight, the first is its comparable flow for winter. I am a convert from 15W-50 to 0W-40 though, I like how the motors runs but now my stupid car leaks oil everywhere. Kind of a trade-off

Nice try to turn this back on me. Let me say again, I am not an oil expert and I don't claim to be. You do claim to be an oil expert. 35 years of experience right?? You said "Secondly, rather than living your life reading and following the opinions of others, why not actually do some testing. Then, whatever your position is, at least you have some data to back it up." I assume this means that you "have done some actual testing" and "at least have some data to back it up". Please tell me that you have torn down some M96 motors and personally viewed the damage done to them running on the oil that Porsche recommends. Tell me that you are not just advising people go against the recommendations of these engineers on a whim. After all, if someone posts here recommending a new chip or headers people typically ask to see the dyno. Some brag about new exhausts and people ask to hear a sound file. You advocate different oil. What evidence do you have to support your position? What sort of testing have you done? They really are simple questions.

I think if you do a little research and look closely, you'll see that 1999 is actually Dick Cheney. Michael

[Image-only post; no author-written text. Original image references:] https://rennlist.com/forums/graemlins/roflmao.gif https://rennlist.com/forums/graemlins/roflmao.gif

Ahhh. The Evil Emperor himself. Yes, I sensed the dark side of the force to be strong with this one.

1999, you seem like good people, but respectfully, you are getting owned in this thread. I don't know about you, but for things above my paygrade, I rely on the advice of others. This includes automotive engineering, aerodynamics, fluid dynamics, etc. Now, yes, I learned a good deal of those subjects in school, but I work with markets and numbers now. Therefore, if Porsche is going to spend millions of dollars to do some work that benefit their cars, I'm going to believe them. Hell, we believed them enough to buy their car in the first place, right? Moreover, to answer your question of 5W vs 15W, it's startup temp. Regardless of temperature, 5W is always going to be a little less viscous than 15W, even if barely perceptibly so. And that's a big help to cold starts for we Northerners. Anyway, you're surely entitled to your opinion, you my good man, have NOT provided any data to the contrary whilst bgiere and Ray have posted quite a bit. Moreover, their data sources are quite compelling. Surely you get the drift why people are starting to get a little more doubtful of your claims, eh?

[Image-only post; no author-written text. Original image references:] http://www.carvelstudios.com/popcorn.gif

I'm gonna party like it's "1999"! Leave him be, your "beef" is with me.................

I hear 15W-50 taste better than 0W-40. That must count for something.... Pic of Alex taken by Kirby at one of our local work on cars days.

[Image-only post; no author-written text. Original image references:] http://emoticons4u.com/sleep/schla03.gif http://emoticons4u.com/happy/674.gif http://emoticons4u.com/sleep/schla14.gif http://emoticons4u.com/sleep/schla15.gif http://emoticons4u.com/sleep/schla01.gif

WOW, that is a LOT of reading. ..... let's see..... where is my owners manual? It's time for an oil change. If I go to a heavier oil does that change the torque spec on my drain plug?????

Just as a side note, I found it interesting that at Sebring last weekend, the RS Spyders were running Mobil 1 0W40. Hmmm...a 480bhp @ 10300 rpm engine running 10/10's for 12 hours straight with a 40 weight oil (in Florida).

Blasphemy!!! It's obviously the reason they lost!! If they had used a thicker brew they would not have had so many mechanical problems. How dare you side with Porsche engineers!!

Don't make me get all Oliver Stone on your ***. It's as plain as day that the whole thing is a conspiracy. Make people use bad oil, then their cars will break. If a lot of cars break, people won't like Porsches. If they don't like Porsches, they won't buy them, and if that happens the company will go broke. And who benefits from that? Well, you didn't hear it from me, but a friend of a friend told me that Dick Cheney went short on Porsche stock... I'm just sayin', is all .

Hehe...I was wondering if I should have brought that up considering they lost to the friggin' Acura's. (On the Acura's first time out, no less.) If I knew that the Evil Emperor owned a share of Porsche stock, I would strongly consider selling my 911. Certainly more so than the Spyder's losing to the Acura's.

Hi, without wishing to debate more erroneous "facts" proffered by 1999Porsche911, the following information may help readers understand the relative viscosities of two Approved and one Non-Approved (15w-50EP) Mobil 1 lubricants - at the oil temperatures most relevant to our engines; The M1 5w-50 formulation is the Canadian and not the Euro version All viscosity figures are in cSt - the higher the number the more viscous the lubricant is! At (20f) -7C (A random cold start temperature) 0w-40 = 530 5w-50 = 761 15w-50 = 1292 At (180f) 83C (A normal coolant thermostat "crack" point) 0w-40 = 22 5w-50 = 27 15w-50 = 30 At (190f) 87C (A typical oil cooler thermostat "crack" point) 0w-40 = 20 5w-50 = 24 15w-50 = 26 At (200f) 93C (A normal oil operating temperature) 0w-40 = 17 5w-50 = 21 15w-50 = 22 At (230f) 110C (An "elevated" but normal oil operating temperature) 0w-40 = 11.3 5w-50 = 13.5 15w-50 = 13.6 At (20f) -7C, the difference in viscosity is very significant. The real meaning of the 0w, 5w, and 15w low temperature ratings can clearly be seen At oil temperatures rise progressively up to (180f) 83C, the SAE40 oil is much less viscous. This ensures rapid circulation and a minimum time spent in lubrication system by-pass and in filtration differential by-pass. Getting the oil's temp to equilibrium with the coolant's temp is a real task as the oil trails behind by up to around 20C for many minutes Modern anti wear (AW) additives begin to become progressively effective above around (130f) 55C. Modern synthetic lubricants function best in a (195-230f) 90-110C range The viscosity band at (210f) 100C for SAE40 oil is 12.5 to 16.3 The viscosity band at (210f) 100C for SAE50 oil is 16.3 to 21.9 From the above you can see that a both M1 SAE50 oils are already in the SAE50 band at (200f) 93C and that the SAE40 oil is also operating in the SAE50 band too! This is one reason why the SAE40 oil (M1 0w-40) is very well received by Manufacturers and a factory fill with such as Porsche, MB, AMG and etc. It has a successful record in tracked engines and is well endorsed by Factory Technicians. It is a very robust oil indeed I have no connection at all with any Oil Company Regards

Doug, Thank you for your analysis. It's very interesting!!

2004 996 C4S @ 65,000 miles. So here is the bottom line question for me. XXW50 is out of the question BUT is there a no-brainer answer to the question of 0W40 VS 5W40 FOR MY APPLICATION?? Thanks in advance I will listen....... eric

Hi, bernocco930S - yes it is all really very simple, follow the latest Porsche TSB, there are about 100 Approved oils Listed there M1 0w-40 is suitable for ALL normal operating conditions and remains one of the best engine lubricants ever made - regardless of price!! A 5w-40 viscosity lubricant is suitable if your ambient is generally above -12f (-25C) Only use Approved and Listed lubricants and don't add any chemical supplements regardless of what you read! Regards

Thank you Mr. Hillary. I forgot to mention that I am in Southern California so I think I read you load and clear. Cheers, eric

BTW Mr. Hillary. Do you know anyone down under that might be in the market for a 1989 930S factory car, one of only 28 coupes made that year? Thanks in advance, eric

Hi, Eric - please send a private message with all details of the car I know Southern (& Northern) California quite well having driven from North to South and lots and lots in between. Your climate is like parts of OZ. I live in the Tropics on the edge of The Great Barrier Reef about 1100kms north of Brisbane Regards Doug Thanks

I guess for those of you without an oil pump. the Kinematic Viscosity is really important? Kinematic viscosity, (CST) measures the viscosity of oil as it flows under the force of gravity and NOT pressure and this measurement does not transfer equally to the flow of the same oil while under pressure. Many of us with an oil pump prefer to look at other important oil ratings. However, the CST DOES play a role in how fast the oil will fall from the lubricated parts (like valves and bearings) when the engine is shut down, allowing you to enjoy those nice engine startup noises. The lower the cst, the faster the oil drains away. It is amazing how the many years of marketing efforts have saturated the minds of so many, but even more amazing is the number of people who simply accept hype as fact and that, some how, lab results transfer to the real world. We all know the claim that startup produces the most wear on an engine, which, of course, is true. What many do not know, is that, as I stated above, at moderate temperatures a 0W40 and a 15W50 will flow under pressure the same volume of oil in the same amount of time. Is oil pressure higher? Yes it is, but flow is virtually equal. Does the 15W50 bypass the filter or other parts of the engine as some here claim? Not at all. Therefore, in this example, wear caused by a difference in oil flow does NOT exist. The difference that does exist is the lack of oil that has remained on the lubricated parts BEFORE any fresh oil gets to it. As stated above, the 0W40 oil will leave less oil on parts after engine shut down than will 15W50 oil. Like that low, low oil pressure at idle? Sure wouldn�t want a hiccup in the engine when the bearings and crank aren�t under proper pressure. Pressure is an important factor in keeping your parts from hitting each other. I wonder how many of these blown engines are due to low oil pressure and how many of these engines that burn oil were damaged because of low oil pressure and no shear protection? I sure hope that those of you who plan on keeping your engine for a long time, do a little research on your own and make an intelligent decision and not just follow the conscientious. Remember, the conscientious proved that the world was flat�.didn�t it? The choice of oil is a compromise. I am not going to rehash all that has been said, but some things are worth repeating. Burning oil is NEVER a result of something good happening in the engine. It is never normal for any engine to burn oil, regardless of how many of you may be experiencing it. Burning of oil ALWAYS results in a reduction of engine performance in late model cars. If you are having piston slap at startup, valve noise, leaking or burning of oil, erratic surging when cam timing changes, rough idle after everything else has been corrected and are running 0W40, why would you not try changing to a better oil and run it for a few thousand miles? There are many on this forum besides me who have done so and stated that they have seen an improvement AND their engines didn�t blow up!!!! If you don�t want to use 5W50 or 15W50, at least get rid of the 0W40 and more to a 5W40 or higher.

1999Porsche911...I don't care what others say about you, I believe you know quite a lot about Pcars, You often give good advice to help others, and you know what you are talking about. That is all.

Hello, 1999Porsche911 - as I said earlier I will not be drawn into a debate over the erroneous "facts" that you promote! Your Post number 73 above is just simply full of misinformation and whats more in the last sentence you say this; "If you don�t want to use 5W50 or 15W50, at least get rid of the 0W40 and more to a 5W40 or higher" 1999Porsche911 - Both the 0w-40 and 5w-40 engine lubricants are SAE40 Oils !!!!!!!! I strongly advise anybody reading Post 73 to submit it to a Professional Lubricants Engineer (not a Salesperson) or a Lubricant (Oil Company) Chemist or Professional Blender to ascertain the true level of misinformation it contains! I will not debate this issue with 1999Porsche911 further as after some months and in various Forums on here he has simply spread very little meaningful information but a large amount of harmful misinformation. I won't waste further time or effort!! Regards Doug Hillary

You actually have 15k more miles on your 04 C4s than I do!! As for the oil debate, I'll just read whatever Mr. Hillary has to say, and follow that advice.

And all this from a guy who says that valve noise at startup is perfectly fine as long as it goes away in 30 seconds. (remember, your previous post remain accessable to all). Sorry, but ANY metal to metal contact causes wear. I kinda like the way you can lump a 0W40 and 5W40 into both being a SAE40 oil, yet a 5W50 and a 15W50 are NOT both SAE50 oils. Funny stuff Doug. But like you suggested, why debate, those who care will find the right answer on their own.

1999Porsche911, I'm still waiting to hear your reply from the last oil thread. The thread where you stated "Secondly, rather than living your life reading and following the opinions of others, why not actually do some testing. Then, whatever your position is, at least you have some data to back it up." I assume this means that you "have done some actual testing" and "at least have some data to back it up". You continue to advocate different oil for our cars. What evidence do you have to support your position on the proper oil for Porsche 996's? What sort of testing have you done on the Porsche 996? How do you explain those that use one of the oils that Porsche recommends and have no oil pressure problems, do not burn oil, and don't have any valve clatter? What is your answer to published reports by independent Porsche experts that the VarioCam plus system in later cars require "lighter" oil to function properly? I will not argue oil with you as I am not an engineer or an oil expert. However, you claim to have 35 years of experience. I would simply like to hear any evidence you have (from your testing) that Porsche engineers are wrong? (Hopefully evidence beyond pointing to any number of problems that occur to some people on this board and stating that it must be the oil.) I am not posting this thread in a negative manner. I would genuinely like to understand why you feel the current Porsche list of recommended oils is wrong.

Doug, that was a fantastic post and extraordinarily insightful. Until reviewing the data, I had no idea how dymanic 0W-40 motor oil was. Living in NY, I get my fair share of cold starts (colder than freezing) now and again even though I park in a heated garage. Clearly your data revealed that the OEM recommended fill is the way to go. What was was most exciting however, was the fact that it stayed very competive as a lubricant with 15W-50 at the high temps that you posted. Dare I say that you have closed this case. Any of the other comments are just hearsay and anecdotal evidence. You viscosity measures set a very high bar in this debate! Thanks a bunch.

Just what does Porsche stand to gain or lose by using one oil over another? They simply recommend the weight that they think works best. I just feel like you keep skirting the issue here. I presume that you don't like to use Porsche's recommended octane either? Nor their coolant? From the 'data' that we've read here, and the notion that tighter clearance engines require a more fluid oil, 0W-40 seems a no brainer unless you're driving on the surface of the sun. Why not just use pure SAE-40 or SAE-50 then? Accordingly to your logic, they would stay on the engine even longer, "reducing engine shear at startup". I'm not trying to nitpick you; it just seems that you've not posted any data to substantiate your claims. Can you post before and after photos of engines that have used the different weights of oil?

Edward, IIRC, this is something that he has addressed and does NOT use the PCNA rec'd coolant but rather change it more frequently using mainstream stuff from Auto Zone, etc.. In all reality though, this "lifetime" coolant we have in our cars really isn't "lifetime".

Correct Dell. I use Peak Lifetime and change 2 gallons with every oil change. http://www.peakantifreeze.com/peak_g...time_5050.html BTW: I just got back from Chapel Hill yesterday. I was only there for 5 hours on my way back from Miami.

Next time in town, shoot me a PM. I'd be down for a drink, lunch, etc.. Heck we can even talk about oil if you want

I thought about it, but I was only there a few hours and had to drive back to ChiTown by yesterday. Didn't feel like getting any nails in my tires, either.

[Image-only post; no author-written text. Original image references:] https://rennlist.com/forums/graemlins/cussing.gif

Yet another bombing run in 1999Porsche911's ongoing oil crusade. He visits a thread tells everyone they are using the wrong oil and leaves with no substantiation for his claims.

Are we done yet?

...that is because there is NO substantiation for his claims...it is all opinion and conjecture...not a shred of real world testing or results. and all experts results and opinions are dismissed as worthless.

I use Mobile 1 oil that flows at the same rate as Aunt Jemima Pancake Syrup (Butter Flavored). Do you think I am hurting my Porsche? BTW - the Pancake Syrup tastes better than the oil. Also, I need to change the Winter air in my tires to Spring air. Should I go to the Porsche dealer to get that done or can a tire shop do that for me?

Do we really need to hijack this thread? I say start a new thread with that question, it's easily good for 4 or 5 pages... oh yea and mention you want to use N02 instead of air.

If you are going to put the wrong air in the tires your probably the type that will not put a factory battery in either or not use German water in the washer bottle YOU DON'T DESERVE A PCAR This is the type of trash that really gets to me

To add to Riad comments...Don't forget to mention the concpet of only using N spec tires....so the thread can be extended an additional 5 pages and maybe rival the "i'd Hit It" thread in OT for length.

What 1999 alway forgets and what oil companies have said for a long time "most of your wear is at start up." Thicker oils do not get to the parts as fast as a thinner oil. Most lubrication is based on oil flow and not the thickness of the oil. Secondly he disregards the fact that variocam uses hydraulic flow to work. If anyone is worried about 40W oil is too thin then think that Heavy Duty trucks run 40 weight oil. In the Boating industry were a boat engine has 3 times the load that a car engine has uses 40 weight too. I'm not gonna say use only Mobil 0W40, but I do advise that you should run a thinner winter temp oil such as 0W40,5W40 or 5W50. The enigine was not designed to run 15W or 20W.

Who said that a 40 weight oil is too thin? I did not read that anywhere. I said that the Mobil 0W40 oil is too thin.

Hello, all SAE40 oils must meet the same SAE J300 specification at 100C Mobil 1 0w-40 with 14.3cSt @100C sits in the middle of the SAE40 range - 12.5 to 16.3cSt. It is in effect quite a viscous (thick) SAE40 lubricant!!! At the HTHS viscosity temperature of 150C M1 0w-40 greatly exceeds the required rating of 2.9cP by delivering 3.6cp. This is almost the same as the next rating up - that for HDEO SAE40 oils - which is 3.7cp. This is one reason why this oil is especially required fo the Cayenne V8 turbo! What confuses people is that some base stocks and the added chemical additives ensure very little "visible" viscosity change from cold (say ambient) to very hot. This is shown by the oils Viscosity Index. An abitrary scale that measures the oil's rate of change from cold to hot - usually from 40C to 100C It appears that Castrol's "Edge" 0w-40 has very similar performance My Professional truck drivers also observed this appearance of a "thin" oil when I commenced using Delvac 1 5w-40 instead of Castrol Enduro 2 15w-40 (which I helped develop) in my heavy (Class 8) 500hp trucks running Interstate. One Senior Driver even refused to drive until he was reassured he would not be fired if the engine failed. Four years and One Million kms later he was a commited user - I still have the pistons/rings/liners and bearings that prove almost zero wear at inspection teardown/reassemble. I replaced these items as a precautionary measure and against the advice of Detroit Diesel - I sure wasted $10k! Regards

Stop it you're embarrassing yourself.

[Image-only post; no author-written text. Original image references:] https://rennlist.com/forums/graemlins/roflmao.gif https://rennlist.com/forums/graemlins/roflmao.gif https://rennlist.com/forums/graemlins/roflmao.gif

What would he know!

When it comes to oil, Doug knows his ****. He also makes educated choices...(obviously as he owns a 928. )

928.......that's the big slow Porsche right??? jk.... I'm actually a huge 928 fan!!

Just for fun I'll post the notes from my Mobil 1 15w50 oil analysis. I switched to Amsoil 5w40 this time, after running Mobil 1 15w50 for the last 2 changes, this previous sample was taken after 13 months and 3k or so miles. "No problems showed up in the sample from your Porsche. All wear read at or below averages for this type of engine, which is a very good indication of normal wearing parts and careful operation. The universal averages show normal wear after 4800 miles on the oil. Insolubles were low at 0.2%, showing good oil filtration. No fuel dilution or anti-freeze was found. Silicon was normal indicating good air filtration. The TBN was 7.4, loads of active additive left. Try 4000 miles for your next sample. Leaving it in place more than a year is okay." I'll post again with my next sample results. Should only take another year or so Andrew

FYI....here were comments from Blackstone on 0w40 used for 7500 miles with 53000 on the odometer: "Our experience with Porsche engins is that they tend to wear very well, and yours is no exception. The universal averages column shows typical wear from this type of engine after 3100 miles on the oil. Wear metals in your sample were remarkably low, and you've run your oil more than twice that interval. Metals were in the correct balance to show no mechanical problems inside the engine. You haven't hurt the oil any in 7500 miles use, and we think you could probably run the oil longer, if you wanted. No contaminats found" I've done 2 more samples since at 7500 mile intervals with similar results.

OK, I'll bite and ask the stupid question... Where do you have your oil analyzed?

http://www.blackstone-labs.com/ I've used a couple different services, but Blackstone gives you the nice paragraph explaining everything, if you don't like interpreting the raw data yourself. In terms of oil for these cars, any modern multigrade will do just fine, on another interesting note, the Cayman 9ff CR-42 4.1L na has a placard listing "Castrol RS 10W-60." Andrew

I just read that the new BMW M3 (V8) uses 11 quarts of Castrol 10w60 oil! How would you guys interpret that?

I think at my next change I am going to use 1qt of 0w40, 1 qt of 5w50, 1qt of 15w50, 1qt of 10w60 and 2lbs of sand!!

Big-A$$-Displacement (BAD) and/or dry sump.

Actually NO,

so now you have a secondary oil sump, making it impossible to get the last 1.8 quarts out of the system, nice...

That end result isn't much different than a real world oil change in a 993, where oil is still in the lines in and going to the coolers in the front of the car, which resulted in the real world a "partial" oil change.

Don't listen to ANYTHING 1999Porsche911 writes. He is the guy that said that shocks were good for a lifetime. If you read the rest of the post you will see that he was disproved many times over. https://rennlist.com/forums/showpost...85&postcount=4 And in this same thread he managed to get caught playing with himself and answering his own posts under a alias. https://rennlist.com/forums/showpost...4&postcount=45

Oh mann...that is Bad indeed! So he wasn't smart enough and got busted! That is really gonna cost him his Integrity and Credibility from now on. Although I admit I've always found his comments to be logical (that, is my opinion and I'm sticking to it.) Oh btw, I have never owned a car that needed to have shocks or springs replaced, and they have all been fairly high mileage vehicles. So I do agree with his statement on the shocks.

Dropped my car off at Rusnak Westlake today for service and was told they will only fill with 0W40 Mobil One. When I asked them to please put in 5W40 Mobil One I was told that they will only put in Porsche approved oils. In other words, NO! They do not consider 5W40 an approved oil for my 2004 C4S, period!

You're still making that false accusation after all these years. Still haven't found a girlfriend, huh, Greg?? Playing with yourself must get boring. If that is true, then I am sure that you can get me banned from the forum since it is clearly against the rules. Oh yeah...you made it up!

Not true I met Greg's wife. Very nice lady btw. Greg, How is KY treating you these days? Is Viken still around? I haven't seen him post in a long time.

Actually oil in a sump is a bit different, being that we are talking about the lowest point in the engine where all kinds of good stuff likes to collect.

Hi, Eric - the Service point made the correct comments and "did the right thing" by using M1 0w-40 in your car. This is the same here in Australia - and officially too from Porsche Australia In NA as elsewhere EM are very confusing and IMHO, poor marketers! M1 Turbo Diesel Truck 5w-40 is NOT Porsche Approved. This is because it is a direct brother of the EM Commercial diesel oil, Delvac 1 5w-40, and whilst it is an excellent mixed fleet lubricant (diesel/petrol) it has not been tested for Approval by Porsche (and as Delvac 1 5w-40 is not readily available) Mobil do NOT appear to market another 5w-40 (and Porsche Approved) oil in NA, here in OZ, NZ or throughout Asia The Porsche Approved M1 5w-50 is not readily available in the USA but is available in Canada, Euro and throughout Asia, OZ and in NZ Regards

Brian, Everything is great here, expecting my first son, second child this summer. Viken isn't on rennlist any longer, long story but he was tired of dealing with people like 1999 Porsche. I don't even know how to respond to that guy, so I am not going to bother, just wanted to post another data point before you risk your car to his advice.

Congrates on the son! Now you have someone to really teach on the track. Its too bad Viken isn't around. Very knowledgable guy. Thanks for the data point for others. I was never considering switching oils. I follow the factory recommendations and I have had 3 very good oil analysis test with 0W40 at 7500k intervals showing that wear is minimal at best in my car.

Hi Doug, as Ed McMahan said.... you are correct sir!... that is exactly the response I received from the man and I politely said, OK. I really don't mind but if I could I would push it up to 5W being here in So Cal.... Oh Well. Doug, check your PM. Regards, eric