Contour Enthusiasts Group Archives Forums Modifications Duratec Performance Recommend Oil

There is some concern that a wider range of viscosities results in an oil that is more viscosity improver (VI) and less "oil"

VI doesn't lubricate the engine, it simply allows the oils viscosity to change as temperatures change.

So, one could make a good argument for a 10W30 in the summer and a 5W30 in the winter. So at least with conventional (non-synthetic) oils, you get more lube and less VI with the 10W30, than with the 5W30 oil, as there is more viscosity spread in the 5W30 lube.

I was pondering, what issues, if any, there would be with a SJ or SL rated straight 30 oil in the summer time. (I'm not talking about 30ND that was used by my grandfather, either.) You still have the additives that protect against acids and what not, but don't get the VI stuff. A bit more lube in your crankcase.

Anyone want to comment on this?

TB