In Reply to: Re: Magnetic Oil Pan Heaters posted by Larry on December 11, 2017 at 14:36:14:
Yes - that is exactly what I am telling you. Here is a graph of the two viscosity curves along with a couple others just for comparison. The viscoity numbers are from the product data sheets for Pennzoil SAE 30, Mobil 10W30, Mobil 0W40 and Rotella 15W40. People see 15W in the grade and assume it means it is going to be a good cold weather oil. It is not. A good cold weather oil in Grade 40 would be SAE 0W40 which will perform just a bit better than SAE 10W30 at temps below freezing (0C).