Originally Posted By: crainholio
My '09 Forester EJ25 has a predictable oil consumption pattern...near zero for the first ~3K miles each OCI, then it starts burning oil at a rate of 1/2 quart per 1,000 miles thereafter. Manual says 7,500mi OCI, I do around 6K miles.
However, this only seems to happen on prolonged highway cruising at 2800-3000RPM. When I flip work contracts and I'm not running a weekly 480 mile commute (230 on Monday, 230 back home on Friday, misc local mileage), it's all short trip mileage and holds the level all the way to ~6K mile oil change. Prolonged high-rev operation seems to drive oil consumption.
I've replaced the PCV valve with a Subaru part, no effect. It seems to burn the least when running Valvoline synthetic high mileage 5W-30 in Winter, and same flavor in 10W-30 in Summer. The worst consumption was with Mobil-1 High Mileage 5W-30, and the valvetrain was noisy at hot idle. I tried 3 OCIs with this M1 and it chewed up oil at nearly 1 quart per 1K miles after it got past 2K miles each OCI. The engine has 109K miles on it and runs well, 24-26MPG if I keep the tach around 2500 RPM on the highway.
Ah man, you just reminded me that I promised myself that I would change the PCV valve in my FXT this winter after a dealer broke their promise to do it for me at my 60kmile servicing...the service advisor was all like, "It's under the intercooler, that's too hard!!!"
I don't have any consumption issues as of now, but I like to be proactive about these things and the valve itself was under $10.
Pulling the IC off intimidates the crud out of me because I've seen for myself how easily those vanes bend, but I need to just grow a pair and do it.