Originally Posted by pepsih
I thought I could just go to the Mobil 1 website and find the TBN number for Mobil 1 5w-30 for you, but it is not listed there, (I think it used to be.) I think I saw it before as less than 10. The higher the number, the longer the oil is supposed to last. It resists acidity from combustion byproducts. From my "research" 10 and higher qualify. If you look at the Product Data Sheet for 0w-40 it is 11.8, which is very high... I'm still sticking with BMW 5w-30. Found it at a local dealer for ~$7.50 and allowed my BMW car club card to get 10% discount.