Q: Car burning oil

asked by on July 28, 2016

My BMW 750Li is burning a lot of oil. I just put in a quart of oil a few weeks ago, and I had to put in another quart yesterday. My car has no oil leaks. I see a little smoke for about 1 minute when I first start up the car. Some of my friends think it might be the oil separator causing the problem. Sometimes when my car is idling I will see a little bit of smoke and when I accelerate, but then it clears up. Could the problem be a valve guide seal?

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Hi there, thanks for writing in about your 2006 BMW 750Li. The two causes of an engine to burn oil are faulty piston rings and faulty valve guides or seals. If the piston rings are faulty, this will allow oil to escape past the top of the piston into the combustion chamber and therefore burn away.

If the valve guide seals are faulty, when the engine is stopped, the oil from the camshaft area will settle down at the bottom of the valve guides. If these seals do not work, oil will slip past the valves and land on top of the pistons. The next time the engine is started, smoke will be emitted from the exhaust when the vehicle is started.

The valve guide seals are most likely the cause of your problem. I would recommend having your oil issue diagnosed and repaired by a certified professional, as this requires an engine overhaul that is best left to someone with lots of experience. If you want to have this checked before moving forward with a repair, a certified technician from YourMechanic can come to the car’s location to diagnose your vehicle’s burning oil.

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