I saw on a show recently (Overhaulin) where the mechanic said Don't use synthetic oil for the break in because it can prevent proper break in and you have problems down the road. My question is "is that true and is partial synthetic just as bad"? The guy said break it in with non synthetic and then you can add synthetic at the next oil change.

 

It has to do with rings seating. I wish we had a Corvette engineer here, or someone over some OEM cars that take synthetic like they do. I know new Toyotas get dino oil, but they expect you to run dino oil, although synthetic is certainly ok and probably better. I think we use Castrol.