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ARModen · 04-05-2010, 08:59 AM

It seems to be a pretty common observation. There are lots of threads on it. My '99 does it at least once a month, and it's got 120K miles on it. The consensus is that it's either an AOS that's not 100% effective anymore or just a product of engine design. I think if the AOS is failing we'd see the smoke more consistently.

One of the other older wiser guys suggested that because the cylinders lay flat and are so low in the engine, oil tends to settle out where it can leak into the cylinders. In a normal car the heads are on top, followed by the valves and pistons. The oil drains down and away from them when the car cools. In a Porsche this doesn't happen.

My personal theory is that there is something (piston ring, valve guide, etc) on one cylinder that leaks as the car cools, but only when the crankshaft is in one specific position. Which is why we only see it once in every 6-10 starts. Someone ought to do a science project and log their crank angle every start to see if they're related.

04-05-2010, 08:59 AM	#5
ARModen Registered User Join Date: Oct 2009 Location: New Orleans Posts: 146	It seems to be a pretty common observation. There are lots of threads on it. My '99 does it at least once a month, and it's got 120K miles on it. The consensus is that it's either an AOS that's not 100% effective anymore or just a product of engine design. I think if the AOS is failing we'd see the smoke more consistently. One of the other older wiser guys suggested that because the cylinders lay flat and are so low in the engine, oil tends to settle out where it can leak into the cylinders. In a normal car the heads are on top, followed by the valves and pistons. The oil drains down and away from them when the car cools. In a Porsche this doesn't happen. My personal theory is that there is something (piston ring, valve guide, etc) on one cylinder that leaks as the car cools, but only when the crankshaft is in one specific position. Which is why we only see it once in every 6-10 starts. Someone ought to do a science project and log their crank angle every start to see if they're related.