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YOUR RESEARCHSmoke at startup after accelerating hard uphill
Leading reported evidence
Install not one
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Performed · outcome unconfirmed
These engines are intended to use high detergent oil and in recognition of that Porsche fitted not one but two de-foaming pots to help remove air from the oil.
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Suggestion
Remember the current formulation of Mobil 1 is quite different to the product that was the basis for the Porsche "Factory Fill" recommendation over a decade ago.
Leading evidence: 'Install not one' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Fill " recommendation over a decade ago' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
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Replace every 5000 km (about 3000 miles) as a condition
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Mine get changed every 5000 km (about 3000 miles) as a condition for the warranty on my engine and on the advice of my indie.
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As a point of comparison, I run my '99 pushing 80K miles from sea level up to 8,500 feet in about 35 minutes over about 40 miles of road with some steep grade.
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The only time I used non-detergent oil was in my lawnmower engines.
These are separate views of the same evidence. Frequency alone does not establish a fix, and these counts must not be added together.
Fill " recommendation over a decade ago
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Suggestion
Remember the current formulation of Mobil 1 is quite different to the product that was the basis for the Porsche "Factory Fill" recommendation over a decade ago.
Discussions that performed work without a confirmed outcome
1
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
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Performed · outcome unconfirmed
These engines are intended to use high detergent oil and in recognition of that Porsche fitted not one but two de-foaming pots to help remove air from the oil.
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If i have it in 3rd or 4th and accelerating hard on steep hills, it produces white smoke after the car sits and is restarted.
It doesn't matter if the engine gets cold or sits for an hour and is still warm. It's an 02 manual with 105k. It runs very well and the AOS was replaced. I am pretty sure it's not that since i don't get smoke any other time, but i wouldn't say that i'm 100% sure.
I am not too worried but i thought i may get an opinion on what it might be.
My thought is either excess oil in the air tubes or oil getting in past worn seals somewhere when the car is at a certain angle.
I believe that it's above a 10-15% grade.
What is the exact oil level ,overnight on the dip stick ,before any hill climbing ?
What rpm are you reaching during your 3rd/4th hill climb ? Above 5K ?
What oil do you use ?
WAG - your engine(not just the sump) is full of oil foam after the hill climb because you are using a high detergent oil.
Have you tried removing the oil filler cap while car is idling? If the cap is HARD to remove + idle turns rough once cap is removed, then a bad AOS MIGHT be the culprit.
Oil is filled properly (not overfilled)? As a point of comparison, I run my '99 pushing 80K miles from sea level up to 8,500 feet in about 35 minutes over about 40 miles of road with some steep grade. The car does not smoke at all. I had the AOS replaced @ 55K along with some other "new to me" maintenance items.
How much smoke are we talking here?
If the rings were the culprits, I'd expect smoke regularly @ that RPM range and load - and the smoke would be instant.
A brief bit of oil smoke at start up and especially after a hard run is amost certainly residual oil that passed through the AOS. The hard run really aerates the oil and the amount of oil vapor inside the crankcase is huge, really it is an oil fog.
The AOS is probably not bad -- though they can fail at any time -- but probably not very efficient, I would hazard a guess it is probably towards the bottom in terms of efficiency compared to the overall population of AOS's.
Not much you can do about it. Well, you could replace the AOS, but that's expensive and not worth doing based on nothing more than my opinion. And you could get a similar inefficient AOS or perhaps one even worse.
There are things you can do to reduce the smoking.
If you do thrash the car try to take a "cool down" lap that is drive easy for a while to give time for the oil vapor that has been passed through the AOS and condensed on the intake walls to make its way to the engine. There will be less oil on the walls to drain into the engine after the engine is shut off and it is this oil that will smoke upon the next start.
Because the engine is running the intake will remain relatively cool so this oil won't just rush down into the engine. And no matter what you do chances are some oil will remain and as the intake gets hot, from heat soaking, this oil will drain down. But the smoking will be/should be reduced compared to what it would have been otherwise.
Be sure the oil doesn't have too many miles on it. I have noticed with my cars the engines are more prone to smoking upon start up as the oil's mileage gets closer to 5K miles. This is even though I give both engines a bit of easy run time after pushing them hard.
As the oil gets used it accumulates combustion byproducts. These tend to increase the tendency of the oil to froth and foam and increase the vapor load the AOS has to deal with.
While the smoking is a bit unsightly the techs see it even with new cars. They tell me that as long as the smoking is confined to just start up, is short lived that is starts to diminish and is gone almost as soon as it begins, and the engine doesn't manifest any untoward behavior and the CEL remains off they don't pay the smoking any more mind. And that is how I view/tread/deal with the smoking when it happens with my cars.
I had a VERY rare puff of smoke from my Boxster - generally after AX sessions - but never any other issues. If this is what OP's seeing, I wouldn't worry.
If you're getting James Bond-grade smokescreens, that's different.
There are two hills that i usually would do this on. The one is four miles from my house and the other is a mile from where i stop.
When i restart my car after the four mile drive from the hill, there is less smoke than the stop one mile from the other hill. This makes sense to what you had said about the oil on the walls.
I never see any smoke while driving and rarely get it on other cold start-ups. I might get a puff of smoke but don't see it afterwards. The aos seems to be an ok solution, but not a great one when dealing with these motors.
I had replaced mine about a year ago and don't want to think about doing it anytime soon.
I never really worry about it, but was wondering what could be causing it.
Based on the amount of smoke you're describing, this to me sounds like the car working as designed. The vapor from the AOS (which would be the PCV in a "normal" car) is routed to the intake manifold so those vapors can be burned off (and the waste gases processed through the catalytic converter) instead of venting them directly to the air. As long as the amount of smoke you're seeing is minimal (which is how I'm envisioning what you're writing), it sounds to me like the car is operating as expected.
You /could/ spend the time to take the intake apart, clean it thoroughly, go for one of your spirited romps, come back, and disassemble the intake again to get a better idea of how much oil is involved - but to me that sounds like a lot of effort to confirm that the car is working the way it's supposed to work.
If the smoking becomes more frequent or
very
heavy (suggesting a progressive issue, introducing the possibility of hydrolock, increasing the potential for ruining a catalytic converter, fouling plugs, etc. etc.), intervene...otherwise, enjoy those drives. Sounds awesome.
Yeah, the amount of bitching i would do taking out the aos again would commit me.
It sounds like all is well and operating normally. I'm glad that's what the general consensus is too. When i tear apart the oil filter, there is very little if any metal and the oil gets changed once a year. That is normally 5-7k miles.
It has 105k on it and i drive it the way it's supposed to be.
Thanks all for your help.
Just a suggestion, but you may want to think about changing your oil more often. Mine get changed every 5000 km (about 3000 miles) as a condition for the warranty on my engine and on the advice of my indie.
Could it be the residual oil collected at the inside bottom of the intake manifolds? They could easily hold 1/2 quart or more oil. Were they thoroughly cleaned up during the AOS r&r?
These cars will smoke at various times. For example, if I start the car after it has cooled down in the evening just to move it into the garage (so, running it only for a few seconds), then start it the morning -- plenty of smoke. Same effect, both before and after a comprehensive rebuild, replacement of AOS, and so forth. I wonder if the boxer design lends itself to this?
Yes. That tendency has been confirmed as a harmless quirk of the M96 design.
The OP's situation seems different - much more smoke and associated with high revs+incline.That indicates a less benign characteristic of the M96. Specifically , the engine will whip up (literally) a lot of oil foam if a high detergent engine oil is mistakenly used. Mobil 1 is such an oil. If you read up on this subject it has been discussed many times by experts(not me !)
The proof and solution are simple. Change to an approved low detergent oil and observe the recommended change frequency(3k miles). It doesn't require much imagination to picture what happens as the crankcase fills with oil foam.The AOS will ingest a lot of it and when the foam settles throughout the intake system.......It will all be consumed when the engine restarts.
This diagnosis of the OP's problem may be wrong but it is easy to test wth an oil change.
Remember the current formulation of Mobil 1 is quite different to the product that was the basis for the Porsche "Factory Fill" recommendation over a decade ago.
http://lnengineering.com/resources/2...s-racing-oils/
"...... the M96 engine and also has superior
foaming
and aeration control, leading to improved oil pressure on the track and less strain on the AOS."
Interesting that there still does not seem to be an alternative to the AOS; reading the AOS information on the site Ahsai linked to helps to better understand why.
I wish the AOS wasn't a weakness on these engines, but it is nice of them to give us somewhat of a warning/indication they are on the fritz, what with the suctioning on the oil filler cap.
Isn't the recommended change frequency 15k or one year?
What lower detergent oil would be good?
I ask this hoping it doesn't spark the usual debate. I just want a good recommendation so i can change the oil when it's due.
I can vouch for this also. Move my car a few feet and move it again later, it will smoke. even with the rebuild. I notice it when playign musical cars moving cars around in the driveway..
Isn't the recommended change frequency 15k or one year?
Not if you like your car and want to maintain your engine properly. 15K is way too long. <5K is good and 3K is much better. I change my oil twice a year regardless of mileage.
I try to change at 5,000 miles and use Motul X-cess 8100 (5W-40). These cars do seem hard on oil, so I change it out more frequently than in our other German vehicles. Not sure if the Motul is low detergent, but both of our indy specialists use it as a top-line, non-racing oil.
All the information is in the link given:
http://lnengineering.com/resources/c...ts-and-fluids/
Frequency :
Of course there are other sources of advice but examine their credentials carefully before you accept notions like 15k oil changes on the M96. And then consider the cost of an engine rebuild if the advice was wrong. The cost of an oil change is trivial by comparison.
Oil type:
Perhaps it doesn't have to be JG DT 40.But it probably needs to be very similar. Let us know if you find an oil claimed to be very similar to JGDT40. But we need specific tribology specs. to believe it. It would be great to have a technically validated alternative. There is is one that is close but I'll leave that for others to discuss in a separate thread.
The OP could be a useful guinea pig by changing to JGDT40 and then let us know if his specific situation of excessive smoking improves ?
None. High detergent oils are the norm and have been for a while. The only time I used non-detergent oil was in my lawnmower engines.
In car engines, run a low/non-detergent oil and get ready for the sludge.
The smoking isn't from the high detergent oil. These engines are intended to use high detergent oil and in recognition of that Porsche fitted not one but two de-foaming pots to help remove air from the oil.
It is unfortunate that the AOS isn't as good at removing oil vapor from the crankcase fumes as the de-foaming pots are at removing air from the oil.
The smoking might be due to a problem but it not from running a high detergent oil. A good number of owners run the same oil -- it is factory fill -- and don't report smoking at hardly any time.
The smoking if not normal will be found to be due to something else, not the use of high detergent oil.
Nobody is advocating 'non-detergent oil'.Nobody.
Some detergent is obviously beneficial.
The M96's foaming characteristic is a problem that high detergent oil will exacerbate.
Changing to an approved lower detergent oil is a simple test to prove if excessive detergent is a cause in this case.It can do no harm.
