QUOTE(Philip W. @ Jul 25 2015, 11:40 AM)
I want to switch from 20/50 to a 40wt on top end .
I was running valvoline 20-50 vr1, our store does not carry 10-40 vr1
I already have a bunch of M1 0-40, their M1 racing oil has 1400ppm. Is 1100 enough?
Yes, but I usually consider a 0w oil as a winter oil.
In oil the first number is the base stock, so in 10W30 oil the base stock is 10w oil.
To get it to act like a 30w oil when hot they add an additive package thus 10W30.
The problem is sludge is often caused by the additives.
This is why I'm not real crazy about 20w50, unless you race (frequent oil changes) or live in a very hot climate...and again you should be doing frequent oil changes.
Good condition engine, more temperate climate and street driving then 20w50 doesn't really make sense to me. But in the same vein neither does a 0w base oil, too far the other direction.