Topic probably been done to death so apologies! Seems to be some long debates online about this topic but with nothing really conclusive.    I know both are approved for use in the PD engine and the 505.01 5w-40 was the original spec but is the newer 507.00 5w-30 spec actually any better in a 1.9 PD? And are there any advantages or disadvantages for either oil?!    What do you use in your 1.9 PD's or are you even bothered as long it meets one of the above specs?