Just wondering what might be wrong with this argument:
Since motor oils in the past could have up to a 375% increase in viscosity and still met SAE grades, why would one have any concerns with using Mobil 0W-40,for example, that stays in grade for at least 3k-5k+ miles? The percentage increase in viscosity from a mid range 30w to a mid-range 40 ( 11 to 14) is only around 30%. An order of magnitude less than 375%. The point being, the viscosity increase of the 40 weight oil is nothing compared to the SAE sequence test increase of 375%, so why worry about. The engine would hardly noticed the increase, but the protection would be greater.
So it seems that we should take advantage of the new generation oils like Mobil1 0W-40 and get the cold, start-up protection along with a HTHS of 3.6/14.3 viscosity at operating temperatures for protection. Forget about CAFE, of course.
Let me know what I am overlooking? Thanks
Since motor oils in the past could have up to a 375% increase in viscosity and still met SAE grades, why would one have any concerns with using Mobil 0W-40,for example, that stays in grade for at least 3k-5k+ miles? The percentage increase in viscosity from a mid range 30w to a mid-range 40 ( 11 to 14) is only around 30%. An order of magnitude less than 375%. The point being, the viscosity increase of the 40 weight oil is nothing compared to the SAE sequence test increase of 375%, so why worry about. The engine would hardly noticed the increase, but the protection would be greater.
So it seems that we should take advantage of the new generation oils like Mobil1 0W-40 and get the cold, start-up protection along with a HTHS of 3.6/14.3 viscosity at operating temperatures for protection. Forget about CAFE, of course.
Let me know what I am overlooking? Thanks