Believe it or not, Marvel Mystery oil does wonders. I have used on high mileage engines when they leakoil, seems to make then stop leaking and run better, smoother. On my older carrera had leaky seals and marvel oil sealed up the engine.
Nice clean new ride for wife 1992 318 is
And with nice new wheels and tires
<img src='http://www.cwo.com/~mikew/ebay/bmw2.jpg' border='0' alt='user posted image' />