2005 xc90. 173k 2.5T. misfire #2 and 4. Timing ok Fuel pressure ok. Running 91 for 8 yrs. Burns about a qt of oil every 1000 miles. After reading this thread now I'm thinking oil is getting past the valves stem seals and burning off.. about to pull the head in the next few days and verify. Compression is 0 psi in 2 and 4 cylinders. The rest are 135-145.

 

Usually the oil goes past the piston rings. Valve guides contribute to very little oil usage.

 

Heads are off and found burnt exhaust valves, now the question is why, any thoughts??