I have been using Valvoline for a number of years, with good results. But I read on here, that Castrol GTX it a very good oil, with moly. I e-mailed Valvoline, and asked them why they don't have it, and they said they put it in there com. oil. But for pass. cars they put in another product that is easier to blend and does the same thing. So was wondering if I should change to Castrol, for the moly, although like I said I have done real well with the Valvoline, change oil and filter every 5,000 miles and don't use any oil, maybe a half pint in 5,000. miles