Burning oil? M103

[John5788]

ive noticed that my 1993 2.6 M103 motor has been consuming a lot more oil since I've installed the 3.27 differential from a 16v (stock in my car is 2.85) and I do alot of highway driving.

I used to only lose 1 quart of oil every 6000 or so miles with the stock differential 3000rpm @ 70mph. but now with the higher gear ratio, the motor is at 3500rpm @ 70mph for highway drives and I lose about a quart of oil every 1500 miles or so.

i have also noticed that when I do let the motor rev higher and higher, my oil consumption goes up more. i believe this might also be the cause of a broken catalytic converter that now have.

the motor has about 144k miles on it, does this sound like a valve stem seal job or should I be looking at something else? i am considering to replace the valve cover gasket, timing cover gasket, and camshaft oil seal if this is the case.

[S-Class Guru]

Yeah, been thee, done that. 300SE with 3.45 diffy.
I think what causes it, at high revs, the upper head area floods with oil that cannot drain away fast enough. The oil covers the intake valve seals, and is pulled past the lOUSY OEM SEALS into the engine. I suffered the same highway oil usage from when mine was new until I replaced the valve seals at 100k. Instantly fixed. Of course, the dealer always told me it was normal oil usage.

And maybe it was normal; we rented a brand new '87 300E in
Germany; drove it on the autobahn at 3500-4000 (and beyond, HeHe).
It ate 4 quarts during our vacation (at $7 per). I had Hertz reimburse me.

DG