my 90 300te 4matic was an oil consuming pig.several things i did helped greatly.change the valve cover gasket .the head has a half moon shaped divet at the back where the gasket fits and this spot was leaking.change the oil filler cap gasket.change to a heavier oil.im currently using 20w50.the 103 engine runs hot and seems to just vapourize the oil.then it gets sucked thru the pvc bypass into your air intake.have a look at the inside of the hose you will see what i mean.all of these things together reduced oil consumption by at least 50%.on a recent trip down east i used only 4.5l for 5000km.speed averaged at 100kmph +.i am planning to do the valve seals sometime.just buying some time with simple solutions.