The Great Oil Debate

First, the preface: currently, I'm running Mobil SuperSyn 15W-50 in my car even though I live in New York City. Nonetheless, I have been thinking about switching to Castrol Syntec 5W-50 when I swap the oil next time. So, I'm reading the Joel Reiser's tech letters over at PCA and thought to stir up a pile of 'oil' again. I know that 1999Porsche has been adamant about 0W-40 not being up to the challenge of protecting the engine when it gets hot, but the cold temp concerns on the hydraulic lifters seems very reasonable. Of course, the point about the engineers lightening the oil as a compromise is a little worrisome too, as in thicker oil is better for the engine but let's not sacrifice our whole budget by building a second reservoir for the lifters. Read on....what do you guys thing? It certainly buoys the case for using 5W-50 at least, yes? Here's some snippets from the PCA site : "15-50 is too high for your car....refill with Mobil1 0-40. The thinner oil is necessary now to work with the hydraulic lifters used in the self adjusting valvetrain. Thicker oils like 15-50 (from any vendor) are too thick for this unless you live in a climate that is hot all year round. The hydraulic lifters each have a tiny little orifice, and the engineers decided that instead of using a separate light weight hydraulic oil, which would need a whole separate plumbing system, they would lighten up the regular motor oil, make it more durable, and then use that for everything. They liked the resulting oil so much they revised their recommendations and now recommend Mobil1 0-40 all the way back to their 1973 models. Even in North Florida, it is often too cold in the morning in winter for 15W-50 motor oil. You may hear awful, scary or excessive valve clatter until it warms up , and the car could have trouble starting at first, or run rough, or send out excessive amounts of smoke."

The Mobil 0W-40 is approved by Porsche and carries both the MB 229.3 and the better 229.5 approvals. At this point I would not use any oil that does not contain the MB 229.5 approval.

Yes, you are opening another can of oil here! If you are not having any problems with the the oil you are using now then switching to 5 - 50w Castrol I don't think will change much. I am a big fan of castrol and used it on all my cars here in Arizona and it seems to hold up to the hot temps very well.

There were a ton of posts in the past where some guys highly stressed the importance of having the 50 up top instead of just the 40, particularly on those hot summer days. Clearly, Porsche recommends the 0W-40, but I wonder if, on appeasing the hydraulic lifters with a thinner oil at startup, they aren't sacrificing a little bit of engine durability. As Mother said, I think Castrol seems the PERFECT compromise. Ah, what a big can of 'oil' it is....

Nuts.

Hydraulic Valves lifters always have a small little orifice, as Joel calls it. How else would you get any bleed down to constantly adjust for play in the tappett. This orifice is to allow oil to escape and not a feed to the tappet. That is why the thinner the oil you use, the more noise you get at startup in warmer climates. In extremely cold weather, even the thinner oil may not bleed out the hole completely. The thinner oil is allowed to drain from the oil chamber while the engine sits, providing little to no oil protection at startup. The noise you are hearing is metal to metal. Hydraulic valve trains have existed for decades and have shown no unusual wear using 15W50. Why doesn't Joel make any comment on what the 0W40 oil does to the engine when it is at a temperature of 220F+? Engine oil protection is not one demensional. Furthermore, at startup, it is more important to have shear protection than oil pressure (but I would rather have both). Shear protection is the film of oil between metal parts, such as the plain bearings. If this protection is too thin (as I contend it is with 0W40 oil), the high spots on the bearings will not be protected reducing the life of the engine.

I have a feeling that Tool Pants was to embarresed to show the can of "SLICK" not in the picture. Besides you ain't liven till you put 50/50 ant-freeze in your tranny.

Maybe that is what Bob uses too.............

You always make good sense, brother. And frankly, the way I drive the car when it IS warmed up, you have definitely convinced me before (on 6speed where you were addressing this before) that having the 50 up top is very important.

Here is another reason why you shouldn't bother with the PCA site. http://www.pca.org/tech/tech_qa_question.asp?id={C1742344-F063-4DA0-80CA-1AA671FFED0A} This guy really should not be replying to people's queston if he is going to be as wrong as he usually is. IF, and I stress IF...the tapping is coming from the lifters, it is because the lifter is bleeding down too fast and NOT because oil is not getting into the lifter barrel. Therefore, 0W40 would be the worse thing you could do to your engine. He should do a little research and see if he can determine just exactly what the difference is in flow rate for a 0W40 and a 15W50 when the oil temp is in excess of 220F. Does he even know how hot the 3.4 engine runs in city driving? Does he know that even the coolant temp will regularly exceed 220F while driving around town? Has he ever measured the almost immeasurale oil temps at specific spots in the oil system? What's the highest spot temperature reached? Is it 300F or 400F or maybe higher? If you drive your car like a normal daily driver, seldom taking it to the limits or into the higher Rpm's, you may not see a difference in the engine wear during the life of the car. However, for those of us that drive to the extreme and would like our engines to still have tight tolerances and crisp performance at 150,000 miles, you are best served by replacing your 0W40 with a higher viscosity. This is even more critical on a forced induction engine and with engines that sit for long periods of time between starts.. It's really not rocket science. The fact is that a 15W50 oil gives you the same protection at 15F as does a 0W40 oil, yet gives you better protection when the oil reaches operating temperature.

1999Porche911, What do you think of the Castrol 5w-50? I see you are in Chicago...do you drive your car daily in the winter? If so what oil do you use in the winter?

I use the castrol or mobil. Currently running Mobil SUV 5W40 for the winter. 15W50 in the summer. 5W50 is ok too.

I have a 2 oil change schedule now: 0W-40 in the winter months (late OCT thru beginning of March) 15W-50 for my DE season (beginning of March thru late October).

I found an oil viscosity chart that drew my attention to something that I had not noticed before. The chart mentions a level of viscosity needed when outside temps 'consistently' fall at the demarcated level. As such, I can't say that even here in NYC temps consistently stay at 10 deg F. As such, 1999's concern that high temps are the greater concern seems pretty well warranted. I definitely think that a 5W-50 has us best protected and am very leary to go the 0W level, particularly since my car is garaged.

Interesting I thought that Porsche went 0 weight for the lifter bleed down. I would think that tappet wear is more of a concern than overall wear from the different weights? I don't know if it's simular, but I have seen how quickly and how much wear can occur when lash is not set right on a cam.

FWIW I work as a service engineer in a large international company that makes big yellow diesel engines and big yellow machines. Our products and components are are expected to last from 15,000 (components) to 100,000 (chassis and frames) operating hours. Proper selection of lubricants is key to achieving long life from power train components. Now it's a free world, and you can choose to use what ever lubricants you like, even down to heavy oils. However, you will not achieve the life you paid for, nor will your receive warranty for failures resulting from using lubricants not approved by us, the manufacturer. Now if you feel that you have more DATA than the manufacturer and are willing to roll the dice with lubricants other than those recommended by the manufacturer, by all means do it. Just don't expect us to pay for your "experiment". I for one will stick with what the manufacturer, Porsche, recommends as I do not have the DATA to provide the security I seek. Cheers,

I'm only talking about the previous recommended weight v. the new wieght of 0.

Be careful with Castrol syntec products... they are not fully synthetic products oil like Mobil 1 or Amsoil.

Check your facts and then you can correct you erronious posting.

It's not completely erroneous... depends on who's definition of "synthetic" you go by... read this and pay attention to the specific compound castrol has removed from their synthetic blend... (this is what leads me to question if it is fully synthetic....) http://www.performanceoiltechnology....obilandpao.htm on another note... I think AMSOIL is one of the best synthetics out there and the company has the data to prove it: http://www.performanceoiltechnology....lvs.Mobil1.htm

Newer cars are designed with tigfhter tollerances and thus need thinner oils to lubercate the parts propperly. The bvelief that thicker is better is old school and does not apply today. Yes there is various reasons for manufactures to recomend thinner oils such as a Fords 5-20W was to hopefully get the F150 MPG slightly higher, but Chryslers recomendation of the thin 5-20 is because the hydraulic components for the displacement on demand does not work well with thick oils. Given the fact that the cams and valve train might be sensitive to viscosity I would not use an unapproved oil for the 996. FWIW Castro 5-50 is a recomended alternative, as are other brands like Amsoil, Valvoline, Shell. I would stick to syntethic oils with a 0-40, 5-40, or 5-50 weight.

Oh no - another oil thread. Why not use Mobil1 5W-50 ?

I have seen this argument many times. Yet, the fact is, the tolerances in areas where the oil passes are no tighter than any high performance engine built 30 years ago. So many people argue that Porsche "knows all things engine", so you have to assume that when they originally specified 15W50 for the 3.4 engine, they found that this oil provided the best shear protection for the bearing, etc. Or maybe now they should be trusted that the 0W40 oil gives the best protection. Since these two oils are completely different on many areas, they were wrong with one of those recommendations. To the best of my knowledge, noone has rebuild my engine that came from the factory with 15W50. The push of 0W40 is a marketing ploy as well as a way Porsche can get a little better performance in the short run along with fuel economy. You could run Olive Oil in your engine over the short run and not have any rpoblem with the engine and that might be fine for those Porsche owners who trade their car for a new one every few years. But is you are serious about longevity of the engine, stay away from 0W40 in warmer climates.

This is a very timely thread as I am beginning to plan my spring maintainance (oil change, brake fluid flush, possibly plugs) and winter / summer wheel swap for next month. Does anybody have a list of approved oils that Porsche currently reccomends for a 3.4? On the same topic, I have also noticed that there are two different filters floating around out there: 996 107 225 52 & 996 107 225 53. Any thoughts between the two? Thanks, Jeff '99 C4

Not available in the states.

So, tell us: which TSB of approved oils should be followed? Number 1? Number 2? Number 3? Number 4? Number? I mean, if Porsche NEVER is in error, then they would have no need for TSB's. Correct?

One supercedes the other. Just order your filter and you will get (in theory) the newest part number.

Does anyone know whether 0w40 was available when the 3.4 was first built in 98? Could this explain why 15w50 was initially recommended? Nothing more than a question, don't read anything else into this.

I think Amsoil 10W40 would be a good compromise if one didn't want to use a 15W50 oil... look at the specs and it comes very close to the mobil 1 5W50; and you can use it in the winter time as well... I do think Amsoil makes a better oil than mobil 1 or castrol for that fact... for those who don't want to change more than once a year I think it's a great choice.

Mobil 1 0W40 was available in (non USA) in 1998.

Have you guys ever sent oil samples to be tested at a laboratory?

I would suggest that you always proceed with the latest information that's available. It's usually representative of the best thinking of the manufacturer at the time. No manufacturer is perfect, even the one I work for. However, we generally have reams of actual data from thousands of machines/engines operating in customer's hands as well as thousands of hours in the laboratory on which to base our recommendations. If WE discover a better method or recommendation, we pass it along to our dealers and customers. Why would I assume that an individual whose sole credential is that he has posted on the internet has more accurate DATA than the manufacturer? It's a free world, and you can use any oil you chose. After all, it's your engine, your experiment. Cheers,

FYI...the newest TSB that superceded all previous approved engine oils by Porsche includes cars 1984-present has no mention anywhere of the 15W-50 oil or any 15W oil for that matter. The lowest weights approved are the 0W and 5W and the higherst weights are the 40 and 50. For me, I run 15W-50 in the summer months especially since I track the tar out of my car here in the Nevada desert. Also, my 996 (2000) has 15W-50 as the approved oil in the owners manual. SO go figure right? I would prefer the protection at higher temps with the 50 weight but we CANNOT get 5W-50 here in the states so 15W-50 is the ticket for hot months. I do however run 0W-40 in the winter months. So if you do the math I do 2 oil changes a year.

Forgot to mention the TSB......1701 group 1 dated 1/2005

I have been rebuilding hot rod engine myself for the past 10 years and can tell you that recomendations have changed over the years. When I was back in high school we were use to the 20-50 stuff for engines, but as we learned todays synthetics provisde a much better film and thus allows the use of thinner oils. They are also more tolerant to thermal break down and are fine for most uses even light track use that we put our cars through. I also do some work on boats and the reasoning behind using thick oils in boats is that the loads on a boat is more equivalent to pulling a trailer up a steep hill. Also consider the fact that a boat engine does have bigger clearances because the difference in thermal expansion when used in marine applications. All I haqve to say go look at a OE oil that was used in the BMW M3 as it was a pretty thick oil and notice the problems they had with some engine failures due to tight clearances. You can run 15-50 with no problems, but I would rather use a 5-50.

Olive Nuts.

Dell: is that 15w-50 made by Mobil one? I live in Tampa FL and have a feeling that I need to change my oil weight.

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http://www.lnengineering.com/oil.html#m96 " What oil should I use in my newer Porsche requiring a "Porsche approved" oil, like the M96 engine? We do not recommend use of most of the Porsche "approved" oils in any aircooled engine, including the 84 and later engines up to and including the 993 that are recommended to run these approved oils. In the search for a "Porsche approved" oil, a quick glance at various Porsche owners manuals for a Turbo and GT2 as late as 2004 showed a recommendation for an API SH or SJ motor oil, so my recommendation is to find an approved oil with at least an API SL rating - an API SH or SJ would be even better. Additionally, try to use a 5w40 rather than a 0w40, as the viscosity with the narrower spread will have a higher high temperature high shear viscosity and should protect critical engine parts better at the upper limits. You do not need a 0w over a 5w until cold start temperatures are under -25C. Do not run any 0w30, 5w30, or 10w30 oil in your Porsche, aircooled engines included! Coupled with Google and armed with the "overview of engine oils approved by Porsche "Porsche approval list", including some oils that no longer have Porsche approval but were approved at some point, here are some suggestions for oils. Remember, we're looking for an API, SH, SJ, or at worse case, SL rating AND meeting the ACEA A3/B3 specification. Remember, the earlier the API specification, the more likely the oil will be to have higher anti-wear additives. One such oil is Castrol Syntec 5w40, which carries Porsche Approval and an API SL rating. Shown below are some alternative suggestions for 5w40 viscosity oils that are not necessarily Porsche Approved, but are of excellent quality nonetheless. I have noted some of these oils meet Volkswagen's 505.01 specification for PD TDI engines, which is very rigorous and in my opinion, is a standard requiring additional protection so much so that Mobil formulated a special version of 5w40 in an API SJ that is specific to the 505.01 standard. If cost was no object and I was out of the warranty period, Motul 300V or Redline would be two obvious choices. Mobil 1 0w40 and Delvac 1 5w40 shown for reference only. HTHS values per published values by manufacturer. We have selected just a few to show: Although Motul Specific 5w40 API SJ has been discontinued, I have run it in my newer VWs with excellent results and have enough oil stockpiled to last a few more years before I have to worry about choosing another oil meeting the 505.01 specification. It had the highest HTHS viscosity of any oil we ever found, min 4.8 to max 5.1 for a 5.w40. Used oil testing showed the best wear results of any oil we have ever run. It was replaced by another Motul Specific VW oil, which now carries a 502.00 approval as well as the 505.01 specification. Interesting point it is the ONLY oil on the market that is a 502.00 oil that meets 505.01 requirements. Currently, we have base-line results (additional results here) for the Motul VW approved 505.01 spec motor oil required by VW. We have been and are currently testing many VW and Porsche approved 5w40 oils and several other non-approved ones to see how they perform in street and track use. Another popular oil highly recommended on the Rennlist forums has been the Mobil 1 Truck and Diesel 5w40 that was an excellent choice up until May 2008, when it was "reformulated" to meet the standards of new diesel engines and hence, is not an API SM/CJ-4 rated oil. As I have stated previously, I don't have the same faith in backwards compatibility of these reformulated products because there just is not the evidence that they will do the same job over the long haul. To this effect, many fleet service related publications still recommend using SL/CI-4 oils in vehicles without particulate emissions filters, leaving the new reformulated oils only for those engines absolutely requiring these low Zn/P oils. Of additional interest is a German Porsche AG Technical Bulletin "2000 Motoroelfreigaben", showing 10w40 and thicker oils are also an acceptable viscosity, which was previously considered as being too thick for these newer, non-variocam equipped engines. If that is the case, Mobil 1 High-Mileage 10w40 or even Mobil 1 MX4T 10w40 may be excellent non-approved candidates, the latter motorcycle oil for track use mostly and not recommended for use with catalytic converter equipped vehicles. The only exception to this are the 2001 and later engines with Variocam, since this system is sensitive to oil viscosity and will throw a CEL if the wrong viscosity is used. Another suggestion is to mix 50/50 Mobil 1 0w40 and Mobil 1 MX4T 10w40, to yield a product in the proper viscosity that is recommended with levels of anti-wear additives as originally recommended by Porsche, with an API SH or SJ rating. "

Stick with the Porsche recommended oil, M1 0W-40, or what's on the latest Porsche approved list. In this great debate, everybody has a champion (or two) and mine are Doug Hillary and A.E. Haas. Both are knowledgeable on the subject and have done alot of legwork in collecting and analyzing data. I implore you read and digest their posts on bobistheoilguy.com and come to your own conclusion. Here are just a few threads regarding Porsche where Doug chimes in regarding the M96 and oil: http://www.bobistheoilguy.com/forums...Number=1663417 http://www.bobistheoilguy.com/forums...1807445&page=2 http://www.bobistheoilguy.com/forums...Number=1455765 http://www.bobistheoilguy.com/forums...Number=1578238 http://www.bobistheoilguy.com/forums...1095144&page=2 http://www.bobistheoilguy.com/forums...&Number=122854 The last link has Doug's comments regarding the Porsche's requirement a lubricant must meet in order for approval: In addition, A.E. Haas has written a great article explaining oil that everybody can understand: http://www.bobistheoilguy.com/cms/in...onth&Itemid=92 While I personally stick w/ the manufacturer's recommendation, Ali has personally put his words to the test on his exotic machinery, including his Enzo Ferrari, Ferrari 550 Maranello, and Lamborghini Murcielago. I believe he is also in constant communication with Ferrari North America with his findings: http://www.bobistheoilguy.com/forums...&Number=961484 If his article has caught the eye of Ferrari North America enough to get distributed within the organization, then it's probably a good read for everybody. If you plan on deviating from the manufacturer's recommendation as well as the approved list, then I would certainly perform used oil analysis at every oil change and trend the history to determine the effectiveness and boundary of your oil selection. /m

Holy 4 1/2 year old thread Batman!

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Indeed. And to put some value on my one-word reply, here's a more recent post from Doug Hillary: http://www.bobistheoilguy.com/forums...1926435&page=1 He makes other comments in that thread so be sure to read it! /m

I saw that as well in the last year or two and actually posted the video. It was from a Grand-Am or ALMS race where the race engineer was talking about the oil they use in the race cars 0W-40!

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Well, after reading this, it all makes much better sense. This is the best explanation I've ever seen on oil weights. Prior to this, everything I read was either conflicting or clear as mud.

Any ACEA A3 oil is perfect for extended drains. If it doesn't say A3, but is 5w-40 that's fine too, it's simply a HD diesel oil and Euro cars are not their target. (Rotella, for example) Don't overlook the Mobil 1 High Miles line. The 5w-30 and 10w-30 are thick. 10w-30 makes A3 and 5w-30 is just a whisker away at 3.3cP. A great winter oil. M1 0w-40 is a fine oil, but burns off fast and is unnecessarily expensive. I'm using some dino and HD dinos for a few quick changes, since I just got the 2002 2.7 w/43k. Here's a good resource.... http://sas-origin.onstreammedia.com/.../pc/index.html I'll stop back later. btw- I've done some UOAs in my VW APR 2.0T. I use Caterpillar, very inexpensive.

I use the Mobil 1 5w-40 and also send out to Blackstone labs. This combo has worked for me since I own the car 2.5 years and 30k miles so I am sticking to it.

M1 0w-40 is a very thin 40, that shears quickly into a 30 weight. I have it in my APR VW 2.0 TSI, which is fine with thin oils, but in no way should people believe it's the ~ultimate~ protection. In winter, sure, it's a fine choice. Neither do I like M1 15w-50. My mechanic says most every blown engine he sees off the track has a jug of Red Top in the rear. Rotella 5w-40 should be a very easy choice to make for every driver. I like to experiment a bit more, with lighter oils as Dr.Hass encourages. However, with the IMS issues, I do believe this is one case where it would be better to err on the side of heavier oil. In my world, I do not mind paying full price for SynPower 5w-40 (more and more places carry it now). Mobil 1 High Miles is a great value and maybe the best product available. I plan on getting it into my car asap to soothe the seals a bit. Feel free to mix and match viscs. Don't rule out dino oils, esp HiMi ones like MaxLife and GTX HM. If you are doing 5k changes, with 8+q capacity, dino oil is more than sufficient. You can leave the old filter in place, esp if you use the same type oil 2x. Synthetic recommendation is for extended drains. Dino oil has actually come a long way since the lame SG/SH recommended in my 2002 manual. I have no problems with dino oil. When I got my car at 42k, I immediately installed some SAE 30 HD oil I had already. Draining it in a few weeks, I have some Havoline 10w-40 for it until deep winter. Havoline has a good deal of moly. Pennzoil makes a good 10w-40 too.

+1 against the M1 products... How is Castrol 5W50 for combined street / track use? how is synpower 5W40 better ? I wouldn't use dyno oils on the track....

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"Rotella 5w-40 should be a very easy choice to make for every driver."" Based on a quick scan of the MSDS for this oil and say M-1 0w-40 oil I'd say only if every (Porsche) driver harbors a secret death wish for his Porsche engine. Rotella 5w-40 oil is a mineral based oil that has a lower boiling point (536F) vs. that of M-1 0w-40 oil (>600F). and in other ways doesn't compare favorably with a synthetic oil like M-1. Get the MSDS for both oils and compare. For Rotella oil call [phone removed]; for Mobil oil call [phone removed]. (I happen to have a digital copy of each around albeit both a few years old now and didn't try these numbers to order more up to date MSDS's. In the case of Rotella oil I see no reason to as long as an oil is not on the approved list of oils for my cars I frankly have no interest in knowing why it is inadequate and in the case of an approved oil I see no reason to duplicate the analysis of Porsche.) Just to show you I'm not biased against Shell oil products, Shell does appear to make several oils that are on the approved oil list: Helix Ultra 5w-40, and Helix Ultra Extra Polar 0w-40 and Helix Ultra C 0w-40, so if one is set on using a Shell oil he has 3 choices recognized by Porsche as suitable for use in these engines. Were I wanting to switch from using Mobil 1 5w-50 oil to another oil I would not hesitate to consider any of the approved Shell oils. Sincerely, Macster.

I don't select oils by the PDS, there's next to zero info on them. Flashpoint, or "boiling point" as you call it doesn't ~make~ a good oil. Rotella has a vast following with other, less ****, Euro car forums. It's far from a "mineral oil" (hello 1994), Shell uses their exclusive XHVI base oil in all their synthetic products. Feel free to chase the mfg specs, but you'll just get the same kind of product, but watered down for API SM spec. Rotella could easy exceed ACEA A3, but Euro cars are simply not their target market. Remember too, many of our oils are N/A in the Euro market, therefore they are never considered by the (marketing) engineers over there. Seeking VW approval is a $500,000 licence for 3 years, that doesn't fit into the business model for many products here. Euro oil are about 2% of the market here (hello!), synth oil itself is only around 10%. Lack of VW spec also makes for a better price, and in many cases, like I explained, a BETTER product. Look over some approved PDS and let us know which oils feature the newest additives. Mfg specs call for mpg and cold-cranking stipulations, superfluous for most of us. I can see the dino exclusion for track use, so I won't get into that very far. However, 15w-40 HD will not fail anyone on the track, HT/HS of 4.1cP, not far from virgin 5w-50...I suppose. One excellent example would be the Conoco 15w-40 w/titanium. Trust me gentlemen, this would be my FIRST choice if I was tracking. The high valvetrain loads in our engine is exactly what diesel oils are developed for. http://www.conocophillipslubricants...._titanium.aspx Kendall 10w-40/GT-1 is about $5/q, or less. http://www.conocophillipslubricants....0TDS%20Web.pdf My BOSCH mechanic is a 30+ year Master Porsche mechanic. He uses Syntec 5w-50 by the drum. He also uses VR-1, which I should have mentioned. I have a buttload of VR1 Racing Synth, that I'll use in time, again mixing viscs, 20w-50 and 10w-30. One issue with Syntec 5w-50 is that it shears to a 40 weight. You may as well start w/a 5w-40. It may be tough on mpg (fwiw) and isn't very good in cold. Not all 5w- grades are the same in cold, many make this mistake. CERTAINLY a 5w-20 or 30 is thinner in cold. Pop some in the freezer next to a 5w-40 and let me know. I avoid 5w-40 in the winter, here's why... That thick isn't great for turbo apps, that's why 0w- oils were developed. I shoot for <5000cSt starting visc, 10,000cSt being the absolute floor. 5w-40 should be fine for non-turbos above 0f. Short trip driving, esp in winter, you are chugging around with extremely thick oil in there. Another thing I like about HD diesel oils it that the specs are constantly upgraded. An ancient VW 502 oil like Syntec 5w-40, the formula gets locked-in to meet spec, no room for improvement. New additives include Boron, Antimony and now Titanium, like in the Conoco oils, Kendall for example. 30 weight Edge has it now too. It's for real, and gets worked into the metal. Google it. If you want a 50 weight, get 20w-50. fwiw, D.H. is a bit of a sycophant with the Mobil spec oil. He's "in" with the "engineers" and won't contradict or question any aspect of product development and merketing. Take it for what it's worth. I use every brand if the price and application suits me. ANY A3 oil is ideal. I want to add here, the new low-saps VW 504/507 are not suitable for USA petrol apps. The sulphur and alcohol in our fuels kills what little TBN it has. Older high additive oils, or new HD oils work best. M1 HM for example has crazy high additive levels, and an older API SL cert, allowing high add levels. I'm going to wrap it up now, but would be happy to share what I can. Valvoline simply makes excellent products, esp the 5w-40 and 20w-50, which actually has some Gruppe IV PAO in it.