Originally Posted By: JAG
That sounds nice but since most of your trips are 10-20 miles, your oil temperature probably will just get done reaching normal operating temp after 20 miles. So your oil will be plenty thick enough (too thick most of the time) on those trips. Wear will be dictated by chemistry of the oil, how you drive, and dirt ingestion, etc. but not much by its viscosity. So you need an oil with great chemistry.
On long road trips, I'm sure you'll spend most of it at light to moderate throttle. So that doesn't put much load on the oil films in your bearings.
1/4 mile drag strips, if it starts at full operating temps as it should for minimizing wear, a 40 weight may be more ideal than a 30 weight. If you don't do too many drag races, then changing to a thicker oil may not be worth it.
This is all about compromises. If you choose a 40 weight all the time, you won't hurt anything but may lose a small fraction of your 600 hp and may lose a little bit of gas mileage. This isn't an easy question with a definite right answer, at least that we can get.
Doesn't or didn't Ford make a supercharged engine that uses 5W-50 Motorcraft oil? Looking into that and how that engine compares to your could shed some additional light on the situation. Clearly Ford did analysis and/or testing and decided to use a 50 weight oil. It probably would shear to a 40 weight oil during use though. That may point to using at least a 40 weight oil after all.
Yes but its a roots blower, I was wondering if a centri would effect my oil decision at all.