Race oil

I use Amsoil Dominator 5w-20. But Amsoil has a good variety of viscosities with high zinc content to choose from. Their 10w-30 produces more pressure, but I forgot how much. A lot has to do with bearing clearances and what your engine builder recommends.

Don't know how much of it is viscosity and how much of it is due to reduced friction (slipperiness), but changing from a straight weight mix of 30 and 40 weight conventional race oil for break-in to the 5w-20 Dominator that I run results in a very obvious higher idle rpm! I have to turn it down every time after I break the engine in and change the oil! It makes that much difference at idle, it certainly helps with wear, HP and running down the 1/4 mile.


http://www.amsoil.com/techservicesbulletin/motoroil/tsb mo-2007-08-08 flat tappet.pdf