Bob the oil guy website guidlines

[madmaxx]

I did not know that all though I doubt BTOG would allow incorrect information. His reasoning appears sound. I played with some viscosity calculators at 40F 10W30 has a viscosity of 439cst! at 212F it is 10.7cst. 15W50 at 40F is 923 cst!!!, at 212 F it is 18. As you can see viscosity increases exponentially as the temperature lowers. Even 0W40 has a viscosity of 426 cst at 40F, just slighly lower than the 10W30.

I imagine any viscosity above 20 Cst and the oil pump bypasses due to the rv in the oil pump lifting. Not only do you have thicker oil, more is bypassing to the oil pan and not even reaching critical engine parts.

Originally Posted by marco246

The info posted by madmaxx came from the site BITOG (Bob Is the Oil Guy) but "Bob" had nothing to do with it. It was provided by a medical doctor named A.E. Haas who is not a tribologist and whose extensive views are not embraced by a large number of BITOG members. Dr. Haas does, however, put his money where his mouth is by running very low viscosity oils in very expensive cars. For example, he uses 0W-20 in his Ferrari Enzo. I believe the factory calls for 10W-60.