996 Engine Longevity

I know I'll end up regretting this, but I'll do it anyway. With all the talk, threads, and experience around 996's in particular, and engine longevity in general, I thought this might be helpful. For background, I have a 996 that I've races in PCA for ten years now. When I bought the car, it was a used street car with roughly 40,000 miles on the odometer. Since then, it was converted to a full race car, first to run in "I Stock", and for the last seven years as a GTB1. The IMS bearing was upgraded right away, but modifications to the engine have been limited per the GTB1 rules: headers, air intake, DME reprogram, under drive pulley, lightweight flywheel. All of the engine internals are stock as built at the factory. Nothing has been opened up. Now, at 66,000 miles, the engine still runs strong with modest compression loss and leak down. 26,000 race miles, or roughly 260 hours at race pace. To reiterate what many have said, engine oil changes occur after every 6 to 9 race days (2 or 3 events). I have used only one oil during the entire time I've owned the car, Mobil 1 15-50. For those who disregard Mobil 1 because of its lack of ZDDP, the 15-50 bottle clearly states an upgraded to the ZDDP concentration, and I always assumed the extra weight would help with high ambient summer heat and race conditions. Rarely does the car get started in sub freezing temperatures. I can count on one hand the number of over revs during the ten years; 3 were rev limiters being hit, and two were "5 to 2" downshifts. Those were the ones that scared me, one being 8800 revs; the other being 9200 revs. I thought for sure that would have killed it, but those were four years ago at VIR. In my opinion, the things that kill engines are 1) thermal shock, and 2) mechanical shock. I always warm the engine up before I go out on track. I allow at least ten, if not 15 minutes of normal idle to allow the water temperate to reach 180 degrees, or normal operating temp before i start to hammer it. It always amazes me how people can start a cold car, and immediately go out on track with their foot to the floor. Think about all those issues with cracked cylinders and heads, where the water temperature in the water jacket may be 30/40/50 degrees, and the cylinder/head temp spikes to 1000 degrees. The engine oil will follow the water temp up, so it takes a while for oil temp to get to a normal operating temp, back to the point of limiting full throttle until maybe 200 degrees on the oil. As to the mechanical shock, there's a reason why so many car parts fail at Sebring. The bumps tear everything apart from the wheels, to the wheel bearings, to the axles, to the trans, to the crank, to the chain tensors, etc etc. Parts that were meant to operate at "X" level of accelerations, measured in G's, and being subjected to much higher G loading during those shock events. Shifting the car too fast creates the same excessive G loads. Slam shifting the gears not only stresses the gearbox and synchs, but puts undue stress into many other engine components. The engine was designed to take a certain amount of time to decelerate from 7000 RPM's to 5800 RPM's, and if you force it to do that in a fraction of the normal time, the G loads spike on all of those parts. These are reasons why all the newer race cars, with lightning fast sequential shifters, have and need very sophisticated engine management software, otherwise the engines with self destruct. Again, I've been very lucky. 26000 race miles on a stock 996 engine. But I've used a few "best practices" when it comes to operation and maintenance. In summary, let the car warm up, take it easy at first, change the oil regularly and watch the shock loading. Like I said at the start, I hope end regretting this, meaning, I hope the next time I start my car, it doesn't explode. I do know, at some point, nothing lasts for ever. But for now, still running strong.

Making me more optimistic about my build! Thank you for sharing your positive experience.

A great datapoint to add to the community, thanks for sharing. I�ve always thought of Porsche as a company that builds very robust and durable sports cars. I believe the 996 is exactly that. They are not perfect; any car built with performance over dependability is subject to failure based on the tolerances with which they are built. But with proper (preventative) maintenance and an owner that pays attention, I feel these cars are as reliable as any 911 built before or after simply due to the fact that all 911�s from any era have their week points. The forum is designed to help those with issues more than celebrating what hasn�t gone wrong given most experiencing the latter have no reason to come here and post. So all the issues you read online are the exception and not the rule. I�ve driven my C4s a lot more than normal over the past few days and turned 110k mi yesterday. It�s amazing to think a car built to such tolerances are able to rack up the miles with no need to be opened up... ask anyone with a Ferrari or Lambo to do the same and they will laugh you out of the room.

Congrats. Nothing to regret, you have a system, you are sticking to it, and it is working for you. Keep up the good work. Even if it blows up tomorrow you have gotten great performance and enjoyment out of the car! Key take-aways for the “rest of us”: 1. Maintain it 2. Warm it up 3. Drive it like you stole it 4. Repeat often!

Thanks for sharing!! I always enjoy hearing from owners who put their cars to the test on the track. 26k miles of track pace is also what I have seen with the fleet of 100 Porsche Driving School cars that I had to maintain. They also used Mobil 1 A40 exclusively ( due to contract requirements) and warranty purposes. 0-40 Mobil 1 Euro until the 5w-50 FS-2 was released, now that;s all they use.No special warm up ritual, they would just start up how ever many cars they would need for the amount of students, let them idle warm up while the students were saddling up. Those "students" were not the best drivers, they drove the cars hard, missed gears, over-reved, burned up clutches ect., but the engines held up.

It's great to hear your engine has lasted and that you have been able to completely enjoy it! If there is one take-away from your story, it is that the M96 reliability is literally across the whole spectrum. From an engine blowing up while idling at a stop light to lasting hard long-term tracking abuse. Don't sink money into making the engine more "reliable". It will never happen. Just enjoy it while it is still running!

Yeah why bother changing the oil or filter? It will just get dirty again!

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I remember when synthetic oil first came out, it was claimed to "never need changing". Calera Police Dept. fell for the hype, they ran a 460 Police Interceptor of 50k before the engine failed..lol

JGIANNONE In my opinion, the things that kill engines are 1) thermal shock, and 2) mechanical shock. I always warm the engine up before I go out on track. I allow at least ten, if not 15 minutes of normal idle to allow the water temperate to reach 180 degrees, or normal operating temp before i start to hammer it. Nice write up. I especially paid attention to your statement, the your ritual of starting and letting run for 15 minutes or so. I have always started all of my vehicles and let them idle a little bit before driving, (Upstate NY has huge variations in temps, not like the South) In the past I along with other 996 owners have been, let's say, not agreed with about this. There are threads here with the Porsche experts claiming, get in start it and drive it. I do understand the factual argument about fuel residual going into oil from prolonged idling, it was just good to hear the other side of the discussion. Thanks again David

1) Curious on your opinion of an oil pan upgrade and did this car have one? 2) What's your opinion on running a performance tune for track duty and did you ever run one? ​​​​​​Thanks

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You're thread is very intriguing and may prove a point that our Porsches love to be driven hard instead of being parked most of the time. If you don't mind, please share with the forum a little more about your car and how you maintained it. What year model? You say you've owned the car for 10 years and have modest performance upgrades per track rules, but do you know the age of the engine? Is it the original engine or an "AT" factory replacement? What IMS bearing did you chose to install? Has the engine every been rebuilt in your 10 years of ownership? What preventive maintenance? AOS? Water pump? Chain guides? etc. Since cylinder bore scoring has become a serious concern among M96 owners, have you thought about having the cylinders scoped as a precaution? If so, in light of the annual track use, how was the health of the bores? Not speaking of compression, but any signs of scoring? Please forgive all the questions, but when I see a thread started like this, I want to know more. We can all learn from you and your experience with this car. Thank you!

I prefer to warm my cars up by driving them like I�m �driving miss daisy.� Then once unto normal operating temperature and oil pressure has dropped to a warm pressure, I let her rip. I pretty much drive like I stole it unless conditions don�t allow it. I drive a bit more friendly when I have passengers. Most passengers don�t like quick turns.....

What about oil starvation? Have you had any issues with that?

In no particular order....Im aware of the argument about not letting a car idle for too long, but I happen to believe that most of that dates back to the days of carburetors and less than perfect cylinder sealing. With modern fuel injection, better sealing, AND, changing the oil every 6-9 days, whatever dilution occurs is offset by limiting the thermal shock (temps changing too fast). The car is a 2003, and the engine is the original engine, with original engine number. As I said earlier, no rebuilds. Yes, the water pump has been replaced twice, the IMS once with which one I don't know, For all race/track use, I had a Motorsport Air Oil Separator installed. This is an absolute must. The OEM just isn't up to track usage, and will fail early on. When they fail, at best you get the tell tale oil smoke out the back upon start up; at worst, you get a nuclear mushroom cloud where a quart of oil gets ingested and burned (hydrolock pressures are the concern). The motorsport part is like $750 vs $150 for the OEM, but is works. It has a Brey Kraus deep sump oil kit, and I run the oil at the top fill mark all the time. Occasionally, if I overfill by a 1/4 of a quart or more, I'll get a little ingestion back through the mass air sensor which will make the car run rough until it cleans itself out. All the normal maintenance items like air filters, plugs, coils are changed on a schedule. I have to believe, even 20years ago at the infancy of these cars, that the Porsche engineers new that they would sell a million of these things, and all over the world, guys would run then like they;re on the autobahn, and, they didn't want half of them coming back under warranty. But, the "German" idea of maintenance and procedures may be different than a world-view lowest common denominator approach. Yes they royally F'd up the IMS issue, and the rear main seal issue is an annoyance, but the cars don't don't fail because of it. I recall BMW engines having oiling and bearing issues. The same thing. Go out on a freezing cold day, start the car and IMMEDIATELY hammer it. The older M3's, and even the newer M%'s and M6's all had these bearing issues. Imagine that, BMW's flagship cars having a design flaw, or, poor judgement/practice/intent. I've raced around people for years. I watch some less-experienced drivers make all sorts of time losing mistakes, only to try to make it up by slam shifting the car on the straights. And I've seen countless cracked rods, pistons, cranks, chain rail failures. To repeat; warm up slowly (any good athlete would say so), change oil frequently, avoid overrevs, avoid shock loading. I think we'll get what those original Porsche engineers wanted.

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Remember that he is at the track, so idling warm up is really the only way. When Jake is talking about starting and driving away, it's gently driving on the street (driving Miss Daisy form), not heading straight out onto the track, foot to the floor. I've always had concerns about warming for track days myself. I'm not at all comfortable flogging on a cold car (big throttle openings and/or high revs), but at the track you're often forced to unless you have time before your session to idle. Doing laps of the pits is generally frowned upon

With shock loading, do you mean shifting crazy? Why doesn't the aos like track? (I have done maybe 15-20 40min stints in my 996. lot of it in hot weather. No problems. But mine is a DD with stockish setup and 200tw tires.)

Clarification. Shock loading is anything that creates a shock into the system, as I alluded to earlier, driving a very stiffly sprung car at Sebring, and pounding over bumps. Full throttle first gear starts over rough pavement would do the same. Speed shifting likewise. And yes, many cars that don't use slicks and aren't set up as dedicated track cars may not have the AOS issue; its when you induce higher cornering g loads that aos issues will arrive; the outer loop at The Glen being a prime culprit....high speed, banked pavement, consistent and/or extended g loading. I went through three or four stock AOS's before I threw in the towel and bought the Motorsport part; no issues in 7 or 8 years.

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You don't need terribly extreme conditions to get the AOS to dump oil into the cylinders. Even spirited runs at the Limerock autocross course got my car smoking like crazy. It cleared itself out when I returned it to street duty.

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You stick with Mobil 1 because it is A40? There are lots of A40 oils on Porsche's list. A lot of independent work has been done that shows Mobil 1 anything is far from the best choice. But if you frequently change your oil (every 3 months or every track day) then I guess the negatives are not as severe. Motul 8100 X-Cess 5w-40 can be had from amazon in 4 large jug cases and shipped free. Is it Mobil 1 cheap? No, but it is A40 and 100% synthetic and proven to be the best oil shy of a Raby product. Edit: I just noticed you said warranty & CONTRACT requirements). Missed that.

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Actually, what I remember is having to "choke" the old carburetor type cars and getting them to "warm up" before driving. On a cold day, the engine would shake horribly until warm. There was no DME or cold start management. You had to get in, pump the gas, apply the choke, get it to turn over, and then keep applying the choke until the engine leveled out. Modern cars have cold start enrichment managed by the ECU. It monitors ambient temps, fuel/air mixture, and emissions on start up. Because these cars dump fuel into the cylinders to give the catalytic converters their "cat food", it's best not to them idle, but instead, drive them. At 10 years and 26,000 miles, I would say it's time for a replacement IMS bearing at your next clutch service. Who in the world advised you to run it that high? 1/4 quart overfilled??? That is one of the things a deep sump is supposed to help minimize. I see you're sensitive about hydro locking from a failing AOS, but have you thought about hydrolock from overfilling the engine oil? Actually, if you read any of the books on Porsche at that time period, you'll see the company was in desperate shape. This was partly due to the stricter emissions standards that were plaguing the aircooled cars and put them at the brink of bankruptcy. A lot had to be fixed and fast. They even hired Toyota consultants to advise them on how to make the factory more efficient. And, they even hired a man from Hong Kong to design the Boxster and 996 model - Pinky Lai Actually, Porsche engineers didn't know squat one way or the other if the M96 based cars would sell at all. In the end, those two cars saved the company, but they didn't sell millions. Don't forget... Cylinder Bore Scoring, D-Chunk, Intermix to name a few other f'd up things with these engines. Actually, we got EXACTLY want they wanted - an engine with 31+ failure modes. However, once addressed by companies like Flat 6 Innovations and Hartech, then they become what they should have been in the beginning.

just another anecdotal data point

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Clifton NJ..home of the best hot dog in the world...Rutt's Hut...

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The evidence in this case is very empirical in nature.

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Thanks! Do you have any pictures? Is your car very similar to a SP996? Do you know how much it weights without driver and full of fuel? Rwhp? They changed the classification for WRL a little so I think they are legal there now. Would be awesome

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You would think after nearly two decades there would be some kind of evidence/list of this much reported FACT. How much longer will it be?

[img]blob:https://rennlist.com/687270ac-ebc3-4098-95d6-d7647cbb4915[/img]A picture. Ten years of development. It weighs 2615 pounds without me, and one gallon of gas. About a hundred more with a full tank.

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agreed. track sessions may be only 15-30 minutes so you don't want to waste track time warming up the engine true, but there are thousands of these positive data points to counteract the hundreds of "failure" data points; they just don't get posted.

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My thinking too. The doomsayers abound; the evidence, not so much...

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Yes, It was part of their contract. The cars were dressed up with large numbers, graphics, manufactures stickers, like race cars, rolling advertising billboards if you will. The cars all had large Mobil 1 stickers and ran Mobil 1 A40 exclusively, Some cars had Michelin stickers and would run Michelin "N" spec tires, some had Pirelli stickers and ran Pirelli "N" spec tires, some had Continental stickers and ran Continental "N" spec tires. They were very particular about what tires went on what car, and that all cars got Mobil 1 put in and not the bulk A40 that the dealership used on most cars, and the oil was not changed "early" due to track environment, but according to Porsche Maintenance Schedule.

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If you know what brand and weight are dealers currently putting in 996s? Do dealers have discretion or is it all 5w-50 Classic Oil?

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Dealers are not "required" to use Mobil 1 or Porsche Classic , but must use an A40 approved oil for warranty purposes., they do have discretion over what brand to use for bulk oil. The dealership I worked for kept Mobil 1 0w-40 5w-50 A40 and 5w-30 C30 as well as "Porsche Classic Oils" on hand in quart bottles. The "bulk oil" brand changed a few times as the oils would loose the approval if not kept up to date. I remember the bulk oil being Kendall/Phillips66 A40 and Castrol Syntech A40 at some point, and would be used in most cars unless a special request was made. I have no idea what they use now, but I know all Porsche Driving School Cars get Mobil 1 5w-50 exclusively

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It's good to have that data point that they all ran N spec tires. It's long been the thought that if you ran an N spec tire that it was damn near impossible to have oil starvation. On another post you mentioned they used 5w50 M1, which that would help bump up the HTHS viscosity and further provide an added level of protection for the stock and unmodified engine. Thanks for sharing.

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Hi Charles, the information about the N spec tires was reported by Porsche. The m96 996 was designed to run N spec tires and not racing tires or R compound. That means the oiling system was just barely good enough to keep from oil starving with N spec tires, but something changes with age/miles on these engines that some people report oil pressure drops on the track even with street tires. I have a few theories on why this happens on cars with some age/miles and not on new cars such as the fleet of Porsche Driving School cars that I was in charge of maintenance, they didn't even have deep oil sumps, and were on track daily at Barbers Track..But I'm not in a position to test these theories, all I can do is implement them on my cars, but that's just one data point. The problem is simple. but the cause/solution is complicated. The simple problem of oil starvation is just two fold, either too much oil leaving the sump fast, or too much oil returning slow. But 9+ quarts of oil should be enough to do the job. I think that the increase in blow-by in cars with age/mileage compared to new cars is responsible for the difference. The theories I have for the solutions to handle that (short of a refresh/rebuild/reconstruction), are still just that, theories. I'm not able or have the means to test them.

Makes sense,, I've seen wet sump corvettes lunch engines shortly after they upgrade to the comp suspension and Slicks.. Accusump is mandatory in that scenario...

Once again, I'll probably end up regretting this, but my experience has been different. My car has been highly modified; much lighter than stock, much lower than stock, and much wider than stock, and has run on both Yokohama slicks and Hoosier A's for years now. From the G force data in the car, it runs over 1 G almost all the time into and out of corners, and in some corners like Turn One at Watkins Glen, I've seen spikes up to 1.6 G's, and have had no oil starvation issues (otherwise, the engine would not have survived the 26,000 race miles). My only answer again is the deep sump, filled to the top line, and the oil warmed before hand. Some of the "stock" classes in PCA Club Racing have dwindled in attendance in recent years, but I've seen many 996 and 997 cars run in H and I stock for years and not have oiling issues. I've also seen rebuilt engines with accusumps that eat themselves. To reiterate, my car is an 03, not an earlier car, so people more knowledgable than me can speak to the upgrades done between 99 and 03. BTW, Kelly Moss that runs the majority of 997 and 991 Cups in IMSA, PCA and otherwise, uses Mobil 1 0-40 Euro exclusively in their customer cars, which happens to be the factory fill on Cups. My opinion (not fact) is that Porsche would not risk their reputation for solely an advantageous marketing partnership. Must my 2 cents.

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In my circles I've had a ton of people attend my classes and this topic comes up. The general consensus with the Cup engines and etc is those prepping the cars don't want to get caught up in a situation where a finger gets pointed at them for something going wrong, because they use their own judgment. They just do what they are told, so they can throw their hands up in the air and say "sorry, not my problem" if something happens. I haven't sent an engine to the track with M1 in the sump/ oil tank since 2002, and have no intention of doing so, unless its to gather data, and comparatives. Most every car comes here filled with M1, none of them leave with it. They will never use it again. That's my 2 cents.

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The oiling system on the Cup cars is of cousre the "drysump" race design and can handle G forces no problem. The 996.2 head design has a better oil return flow to the scavenge pump than the 996.1 head. On the 996.1 the rare (not available in the US) x51 had a dual stage oil scavenge pump on bank 2 to help with oil return on high G force. the 996.2 X51 did not need this extra scavenge pump as the head was redesigned with a better oil return to the scavenge pump. The 996.1 is the most likely to experience pressure drops at the track, some people have even reported pressure drops on high G force turns on the street with street tires and a deep sump on cars with some age/miles. I think a lot of improvement can be done on the oil system. I have a lot of ideas to improve the oiling of the 996.1 that some of the top engine builders are probably using to keep these from spinning a bearing. Like I mentioned above, all the Porsche Sport Driving School Cars are completely stock, no deep sumps, and all run Mobil 1 5w-50 exclusively on track daily for years, and change oil once a year.

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I have posted about this in the past, but to re-iterate, I have owned 7 996s, 3 early and 4 late (1 C4S). One of them had an X51 pan. I have also driven 3 other 996s, 2 early and 1 late on track and instructed/observed countless others. Even though I have never experienced a failure (over 100,000 miles of mixed street and track use with different tire and suspension set ups), every single one of them has oil pressure visibly drop on long right turns as per the factory gauge, sometimes down to 1.5-2 bar. I started taking VIR's turn 1 in 3rd gear (~3000 rpm or so), which results in a steady pressure with no perceptible drop. I have also owned and tracked turbos and a GT3, which show absolutely no oil pressure drop in any turn including with slicks. This always made me take notice, but I have not done anything beyond an X51 baffle which has had limited observable benefit. Of course I used to track/race BMWs which didn't have a factory oil pressure gauge, so who knows what the pressure was doing. Those cars did starve for fuel with under half a tank under the same conditions... and go through wheel bearings... and ball joints, and shock mounts, and water pumps, and radiators and and and... In comparison, the 996 has been a great trade, and they're more fun

My E46 330XI with a factory Msport package (Factory delivery optioned...) ,, Was a ton of fun,, it didn't have the e-ticket ride power my C4 has.. But that car could hang HARD in a turn.. My 69 911T wasn't as power fast as the 996,, but I loved the dry sump air cooled engine,, and that car was just a go cart, in may ways it was more fun than the 996,, It did have Magnesium Carerra Front calipers.. and 15x8 wheels on all 4 corners.. Ran a square setup with goodyear's... I really miss the feel of a all manual car,, with 8 fuses in the fuse box..

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I'm pretty sure what Porsche really cares about is negative publicity, and that they know very well all failure modes and mitigation measures of M96 engines, so if we find out what oil they are putting in 996s we can get valuable information from them. Our first oil change was at the dealer. We had no idea additives and viscosity and base stock etc could be important to engine longevity, so didn't think to ask what they put in our car. As you mention they have bottles and bulk so if I ask them now not confident will get accurate information, they didn't seem to care about our older model didn't even wash it.

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A lot of dealers don't use bulk oil, they just use Mobil 1 in bottles, but if they use bulk, you can be sure it's A40 Porsche approved. Porsche probably uses Mobil for factory fill because Mobil has deep pockets, If they screw up a tanker full of oil for the Factory assembly plant, Porsche will be digging into those pockets..

My 69T still had the "Use SHELL oil only" sticker in the engine bay when I sold it.. LOL

One of the points I was trying to make was that the brand of oil is far less important than the change interval for its intended use, and its temperature when you lean on the engine.

What are the "go to" oils today? DT40 is just to expensive (for me) to ship to Hawaii knowing it's going to get dumped in 6 months (2000 Miles)

Rennlist + engine thread = oil thread I am willing to shell out my money for DT40, I just wish there was more data. I can't find any hard data or independent testing on DT40. For all I know it is 50% maple syrup.

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Hmm, that would explain why it's more expensive!

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Like the Swamp Oil Salesman from 120+ years ago "This here oil will cure all your Ailments, Baldness, Diarrhea, AOS, Bore Scoring and IMS, one bottle is all it takes!!!"