There is plenty of evidence that mixing *modern* synthetics with dino is fine: Pros: (1) the label says so - think of the liability if it was not so (2) I've done it MANY times - in fact used to mix 1/4 (3) most major brands sell pre-mixed blends (4) API specs require that all "SH" oils be compatible with other "SH" oils Cons: One mechanic's after the fact opinion. Grant