I use MB spec Liqui Moly. Runs around 10 bucks a liter. I change it every 40-60k, easier then a oil change. But the smell is not easier. Dispose this stuff immediately. I learned the hard way! :)
LIQUI MOLY - Motor Oils, Additives, Car Care - Products - Hypoid Gear Oil (GL 5) SAE 85W-90