quote:
Originally posted by pscholte:
That is an interesting test of "theory" and "practice." Mobil 1 0W40 is, in its latest formulation, an "Energy Conserving" oil (says it in the "doughnut"), but Castrol 0W30 is not. Yet, from what you say, I'm guessing you'd have the same gas mileage results when comparing the Castrol 0W30 and the M1 0W40. So how is that in testing one gets the rating at a 40wt and the other doesn't as a 30wt?