it's really bad that oil was change each 20,000 miles with BMW oil, which is not full synthetic already (just read Bob is the Oil Guy). When I was read this I was shocked so moved to Castrol and now to Mobil 1 5W-30 and 0W-30, but do every 5,000 -7,000 miles.
Just to add
1. BMW oil is Group III hydrocracked, it's not full synthetic oil at all and it's = Castrol TXT Softect
2. Only three brands in US are full synthetic are Mobil 1, Amsoil, Royal Purple
3. German Castrol 0w-30 (it has the red label and says on the back, "Made in Germany) is claimed to be full synthetic, but it's made in Germany.
4. Redline is a Group V PolyEster based oil
5.All other Castrol, Quaker State, Pennzoil, Valvoline "synthetics" are a Group III hydrocracked oil.
6.Used oil analysis has shown the BMW oil is generally depleted at 10,000 miles. Running it longer results in excess wear. It is highly recommended that you change your oil once between each BMW recommended interval (approx 7000-7500 miles). If you want to run your oil the BMW recommended interval, I would suggest that you use Mobil 1 0w-40 or Amsoil 5w-40 and change the oil filter at 7500 miles. I would encourage a full oil change at 7500 if you want your engine to last.
BMW CCA Member, Capital Chapter
Last edited by phlfly; 09-24-2012 at 08:29 PM.