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2000 C5, manual, cammed (in 2012), HPDE car, ~40kmi. Have an accusump. No oil leaks. No oil in coolant, no coolant in the oil. I'm original owner.
Normally use ~1/4 - 1/2 quart during a track day and see about the same amount in my catch cans. All depends on how much high rpm w/closed throttle I'm using.
Was getting ready for last weekends track day and was surprised to see it down a full quart. Drove to the track and had to add more. Added more through the day. Got home and it was down again. Normal amount in catch can.
All valve stem seals are still in place. All spark plugs are clean. Compression is ~200 psi (200, 210, 200, 195, 200, 200, 207, 200). I need to find where I wrote down the compression last time.
No unusual engine codes.
If the valve guides wore, wouldn't I see the oil on a spark plug?
My accusump valve was sticking and not functioning properly. I bought a new valve kit but traced the problem to the little sensor (looks like an oil pressure switch). Maybe your valve is sticking and your engine is "hiding" oil in the accusump(?). Sounds like you've covered the mechanical basics. Yes, if guides or rings were bad you'd see it on the plugs.
Lol, don't think it could be hiding that many quarts! A few years ago it was sticking. Was able to disassemble and unstick the valve.
My compression measurements may be off. Realized the schrader valve wasn't in the hose. I remove the valve when I use the hose to pressurize the cylinder during valve spring changes.
Maybe I'll just go with a full vented PCV system just to see if the consumption decreases. Car has a closed loop speed density tune so the bypass air shouldn't throw it off. Car won't be driven much until next year.
Sudden Oil Consumption
