Originally Posted by tromero

I picked up my 997.2 on 11/25/08 and assumed the oil was full but cannot be sure. In January I got a warning light showing I was low on oil. I added two quarts and was full again. Now, scarcely a month and 400 miles later I am low another quart! Surely this cannot be normal. I don't see any oil spots beneath the car so it's not leaking any so it must be burning it somehow.

Originally Posted by ragdoll

These are characteristics of a DI engine.

Here is a German technical paper on general oil consumption during break-in. This engine was at full load for the entire test and still didn't stabilize until about 400 hours of use.


Different engine all together, but you can kind of get the idea.

DI engines do not come without fault. Perhaps some of you have read my write up already on these. These engines will have performance issues after some moderate use.

Here is the over simplified short version... the intake vales no longer are washed with fuel. They are super heated and dry. As most of the left over fuel and blowby oil is recycled from the cylinder chamber back through the intake, that residual oil and those particulates of fuel that were not burnt now are in direct contact with those hot/dry intake valve. Some of that bakes itself to the intake valves. Over time(from a few thousand miles to maybe 15,000[I am guessing since this DI engine is too new still]) the timing is pulled back to deal with the lack of smooth air flow via the intake valves.

Because it comes on so gradual over the 1000's of miles you won't feel this. But your car is getting slower and less fuel efficient.

That actually is the short version. The long version explains how I studied the recycling system that Porsche made and how internally the concept it's very similar to Audi's. And you may already have heard that the FSI(Audi's DI design) is plagued with this issue severely, especially the RS4 and R8. But I won't get into all of that.

This isn't to say that all the oil you are burning up is going on your intake valves. That's silly. That was just a side note. The oil burning goes back to the beginning of my post, normal burn in for a new engine(within reason). Some of your oil burning is NOT normal but will most likely taper off in the coming months. But this "missing" oil in your engine is on your tail pipe or getting layered up in your Cat. If you heated your tail-pipes up to 1000 degees for a while you'd see what your intake valves are looking like, baked on carbon and residual gasoline particulates that will only come off with an atomic bomb blast(or hours of cleaning).

One more thing. Once your oil consumption tapers off, I COMMAND you(ha) to send a sample of your oil to BlackStone or similar oil analytical labs for a review. Plenty of DI engines are also seeing critically high fuel dilution in the oil. And when your oil stops going down on the readout, it could mean it's still burning but being replaced with raw fuel instead. High fuel dilution in oil means the flash point of the oil decreases at a frightening degree. I'm seeing fuel dilution at 5-6% in some! That is 5-6% of your oil pan is gasoline mixed in the oil. That is serious trouble. 1-2% is "normal". High fuel dilution is an engine destroyer.

EDIT: I have absolutely no affiliation with BlackStone. I am just an Engineer outside the world of automotive.

Originally Posted by jacques1960

I have 23,000 miles on my 2009 997.2, flog the ***** on the track once in a while, drive fast and have never - repeat never - had to add oil.

Originally Posted by Gpjli

This is how NOT to do it. The cel does not substitute for properly monitoring the oil level on a regular basis. It is a last resort warning to tell you that you are at risk. Your car deserves better than this.

Originally Posted by Michaelwww

What model are you driving? I use about a quart every 4000 miles on my 09S with 26k miles. Just blame it on the high compression engine and not worry about it unless the CEL comes on.

Originally Posted by Michaelwww

Yeah? No kidding why dont you read and comprehend what I posted? Oil consumption in and of itself is not a concern per the owners manual. Oil consumption along with a CEL needs to checked. The whole cause or symptom routine. Check engine light not check oil.

Originally Posted by Gpjli

Op's concern about oil consumption is what started this thread as far as I can recall. If this has drifted off the topic best to start a new thread. And what's with the attitude?

Originally Posted by nottoshabi

@ Gpjli. Agreed to your post I just can't seem to pull the dip stick out is it hooked to something, doe is it have a clamp of some sort or do I have to unscrew it? If I just pull it out straight like you will do on any other car it wont come out. I pulled on it a quite hard, did not want to break something or bend the metal rod. Thats why Im asking.

Originally Posted by Michaelwww

You are the one who stated my car deserves better, not kool. Did not quite follow that... just pointing out that oil consumption and a CEL could be a problem, otherwise not to worry. Sounds to me like reassuring words to the OP.

Originally Posted by daberlin

So I went to Auto Gallery today for their '30 minutes with a Porsche technician'. It was a really great event - Jim at Auto Gallery is an excellent guy; very patient with dumb questions and very knowledgeable. During this discussion today we talked oil consumption. Jim stated that Porsche's acceptable guideline for oil consumption on a 997.2 is 1 quart per 600 miles. This seems near inline with the discussions held in this thread. But here is the other fact that I wanted to pass on to everyone - also discussed here. Pay close attention to how you check your oil level. A few weeks ago after originally reading the thread, I checked my oil level after a 30 minute drive. I 'thought' I was on level ground when I checked - it showed half down on the display scale - this after about 700 miles since my last service. Today, when Jim checked my oil level - now 200 additional miles later - it showed I was fully up on oil. No minor or excessive consumption, no issue.

Originally Posted by Gpjli

Ahhh got ya! Message board communication can be hard sometimes. If someone just reads your post they might think that you were waiting for your cel to come on...well, nevermind. Quart for 4000 miles is good. Not everone will be as ok with their oil use as you are. You are correct that most of the time it is not indication of a serious problem though. Thanks for the clarification.

Originally Posted by chance6

If you convert the 400 hrs to approx mileage, that's about 14000 miles, at least for my DD where I avg 35 mph per tank, city/highway combined. Those numbers make a lot of sense to me.

HOWEVER: not sure I buy the huge performance hit due to intake valve accumulation.