Cold weather and oil viscosity?

[RickB]

I've been running Valvoline 20W-50 racing oil and it's great.

I'm wondering though if I should switch to a different viscosity for the cold 12F driving this winter?

 

[Mickey Richaud]

Rick -

My vote would be to leave well enough alone. I believe 20W50 is effective down to 0 degrees fahrenheit. If the car spends most of its down time inside, it won't see extreme temps anyway.

Mickey

 

[RickB]

If the car spends most of its down time inside...

No such luck, so still stick with the 20W-50?

 

[Mickey Richaud]

Your call, really. I'm not a big fan of switching oils, if possible, but I can see how, in your case, it might be a good thing. Still, 20W is supposed to flow OK down to 0 degrees. But again, you might not want to chance it...

Gosh, did I seem wishy-washy there? :blush:

 

[JPSmit]

Gosh, did I seem wishy-washy there? :blush:

maybe :lol:

 

[RickB]

What does everyone think of adding some MMO in the winter?
If I'm a pint or two low, I could top it up with MMO.

 

[Pythias]

the "book" says...

down to 41 degrees F (5C) 20w40 or 20w50 ...
from 41F to -10F (5C to -12C) 10w40 or 10W30
below 10F (-12C) 10W or 5W20...

This is depending upon brand .. and is a shortened version listing oil brands specifically, such as Duckman's, Sternol, Esso, Mobil, Shell, and BP.

 

[BugEyeBear]

Typically I use 20W50 just for summer "Hot & Hard" running, then I use 10W30 or 10W40 for cold winters (freezing & below).

At freezing temps cold 20W50 is roughly twice a thick as cold 10W30or40. So turning your cold engine over will take twice the effort and oil simply won't flow as freely. Since your battery is typically also weaker in the winter this extra effort is further exagerated.

I'd recommend switching to a lower cold viscosity oil for winters, and DEFINITELY stay away from a straight 30 weight as that's stuff's like MOLASSES in the sub-freezing temps (roughly 3x as thick as a 10W oil...).

Have you tried the new 5W50s that are available? Theoretically the best of both worlds!!

"Cheers!"

-Bear-

 

[BugEyeBear]

For your reference:

SAE 10W40 at 40degreesC has a viscosity of 95.41
SAE 10W40 at 100degreesC has a viscosity of 14.0
SAE 20W50 at 40degreesC has a viscosity of 170.9
SAE 20W50 at 100degreesC has a viscosity of 18.5

So you'll really notice that the 20W is almost 2x thicker at 40degreesC, but you won't notice much difference once the engine has warmed up to 100degreesC.

"Cheers!"

-Bear-