Mileage effects on cold weather performance

Patman

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May 27, 2002
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One thing I have been curious about for a while now is how much of a difference is there in the cold weather performance of an oil once you put a few thousand miles on it. I’m speculating that the base oil plays a big factor here too. But generally speaking, would a 0w oil still be a 0w oil after 10,000 miles or would it be more likely to degrade enough that it would only test as a 5w oil?

It’s too bad that the oil analysis labs don’t also test the cold cranking on used oil. For people who live in extremely cold climates that would be valuable information to have.
 
I can’t imagine that an oil that is thinned out by fuel would actually have better cold weather performance though

it would if it's a gas engine. As far as the hydrocarbons are concerned, you just added a very thin base oil to the mix. But still not a good thing.

And yes, used oil is allowed to slip one winter grade. That's why they are often so close to the upper limit of the grade I suppose.
 
The pumping viscosity is allowed to increase by one grade. It's tested after the Sequence IIIH test, which is a severe test in terms of oxidative thickening, and which allows a 100% increase in KV100. The oil shouldn't thicken nearly as much after 10,000 miles of normal service.
 
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