How does Mobil 1 0W-30 compare to the German Castrol 0W-30? The Mobil 1 would be much easier to find and if they produce similar results then it does not matter that the German Castrol is so hard to find. I assume that the two oils would flow at about the same low temperature. How do they protect at high temperature? Some peopel here say that Mobil 1 tends to be a little thin and the German Castrol at higher temperatures is apparently almost like a 40 wt.