BMW Repair: BMW 528i oil consumption, e39 528i, valve seals

Question
I have an E39 528i, 1996 model which has done 150,000 km. Recently one  of the cylinders stopped firing & the reason was an oiled up spark plug. The other spark plugs were also foul so I changed them.

My car consumes oil (1 liter for 1500 km) but there is no smoke even on accelerating from a standing start nor does anything show up in the  emissions. The mileage of the car is also very good. Possible culprits as per the mechanic are piston & rings OR valve seals.

Can you suggest the best way to exactly identify the problem so I can get the right thing fixed and not go the hit and trial way most mechanics do? The compression test is fine, the other issue is the car is mostly driven by my wife to & from from work (5km each way) with many red
lights.

Cheers,

Janak.


Answer
If you're not smoking, I question if it's rings or valves.

are you seeing leaks? the rate you're losing oil equates to about 1 drop per km.

What weight oil are you using?  might wantt to try a heavier second number. (ie:  change from a 5w to a 5w30, or from a 10w30 to a 10w40)