Klaus,

I agree with your head gasket/rings assessment. I've also read just about every post in every forum pertaining to replacing valve stem seals, and it seems there are two stories. Some have left the head on, compressed the springs with a special tool, and devised a method for catching the valves before they fall into the chamber while they replace seals. Others have removed the head and reconditioned it in peace, or replaced with a rebuilt head.

I'm going to begin pricing out this job, because the universal agreement is that it's a horrible PITA either way. I'm very interested in discovering if the indies remove the head or not. That would drastically affect shop hours spent, I imagine.

I agree this isn't an especially pressing matter, except for one thing. I've already begun getting the occasional P0441 code warning of catalytic efficiency failure, and my research says that pushing a lot of burned oil through the exhaust causes that failure prematurely, so the longer I wait, the closer I may be to also force my hand in replacing the cat.

Here's another thought. Can leaking stem seals contribute to either a rougher running engine, or reduced gas mileage?