Yes it's been asked alot before. For breakin, I've used Rotella 10-40. There has been some question about the zinc composition which is needed during break-in. I found some STP red bottle additive which is supposed to have alot of zinc. GM EOS oil supplement is also good but getting hard to find for some. After break-in, it's just your own preference. I like Castorol because it seems to hold good oil pressure compared to others. Bottom line change oil often