Richard Koop

Does anyone have a good understanding of how oil is kept from draining back into the oil pan when the engine is shutdown? Is the oil filter (with those o-rings) supposed to do that or is there a check valve in the engine or something else?

Reason I ask is that my wife's car had the rattle at startup and replacing the timing chain tensioner, camshaft adjusters, magnets and sensors fixed that (almost 98%). Timing belt was tight so I didn't touch that yet and would rather not. There is still a minor rattle but it only happens if the engine sits for a while. My thinking is the oil drains back into the oil pan and doesn't stay up in the high parts of the engine. After starting and once oil reaches the correct pressure (fraction of a second) the engine is perfectly smooth and drives well. I think the P0016 code is caused by no oil in the upper area of the engine at startup.

Maybe the oil filter o-rings aren't holding oil from draining back? I'd really like to get rid of that check engine light. Thoughts?

Richard