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Posted by: Philip W. Jul 25 2015, 09:40 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?

Posted by: Mark Henry Jul 25 2015, 10:15 AM

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.

Posted by: Philip W. Jul 25 2015, 10:27 AM

Thanks Mark.
With all the discussion recently I decided to see if tthe10/40 would run cooler as some have said here, and the 20/50 seemed even for our heat too high. Car has rum hotter since I switched to it. But I have the 0-40 left over from the boxster, WI h was what they recommended for year round in that car.
I'll try to find some 10/40 with at least that amount of zinc. Might go with the Mobil 1 v4 racing oil.
Sludge is a factor for sure. Had a friend with a Volvo that had severe sludge oroblems, they wanted to replace the enginge. He switched to conventional oli after just having it cleaned out as best they could and that was 2 years ago no more issues.

Posted by: Mark Henry Jul 25 2015, 10:57 AM

Phillip the reason I like the delo 15w40 is it's got a high base stock number and because it's so cheap I will change my oil more often. Here I get it for $65 for a 20 liter (about 20 quarts) pail.
Also doesn't hurt that Henry at Supertec uses it, it's a lot like the old RottilaT and the fact it's the same oil I use in my tractor.

You also hit upon another thing about 20w50, to me a thicker oil would just cause even more heat.
0w oils are really for meant for modern cars to meet fuel economy, and the engine is designed for it.