Originally Posted By: Stang40
My 4.0 mustang calls for 5W30, I don't live in a cold area, but would 0W30, like M1 AFE or GC hurt anything?
German Castrol 0w-30 does not meet Ford's WSS-M2C929-A spec (or any of the preceding Ford specs) for a 30 weight. Mobil 1 AFE does.
AFE and GC are probably the most radically different motor oils, carrying the same weight rating, you'll find in the United States.
If your warranty, or extended warranty, is over you can run German Castrol if you would like to give it a try. Just cause it doesn't meet Ford's spec doesn't mean it's not a superior product. Because it certainly is. It's a heavy, sheer stable, PAO based 30 weight that meets BMW's Long Life specification.
It costs a lot more money to put that oil together than it does to fill the other bottles with Group III+ wonder fluid.