Bought mine at 15,400 miles so before that I do not know but from there to 152,000 I have used Mobile 1 15-50 exclusively. But---I do live in TEXAS and often drive in 105 temperatures so maybe a thinner oil up north will work. Tried Fram and Wicks filters and blew out both of them. I use Mopar 090 from Walmart and never had a problem.