this is what crane cams says about synthetic, which is neither too thin or not enough additive.
This is copied and pasted from an email sent
to crane cams
(Hello,
Yes, synthetic oils do not provide the proper interface between the parts that are attempting break-in.
Flat tappets for instance, do not get the traction needed to initiate the spin necessary for proper break-in.
Thanks,)
THAT is why you don't use synthetic to break in a cam it is too slick. this is merely my theory, but I also believe this is one of the basic reasons they went to roller cams in so many of the new engines, not to mention the fuel consumption.
The only problem I can see is that there are at least 2 companies (Valvoline and Royal Purple) that are manufacturing full synthetic break in oils. I suppose Crane may not have tested those new break in syntetics yet, as they are fairly new on the market.
