-
Hi Guest!
If you appreciate British Car Forum and our 25 years of supporting British car enthusiasts with technical and anicdotal information, collected from our thousands of great members, please support us with a low-cost subscription. You can become a supporting member for less than the dues of most car clubs.
There are some perks with a member upgrade!**Upgrade Now**
(PS: Subscribers don't see this gawd-aweful banner
Hey - did you know if you click on the title of a thread it will take you to the first unread post since you last visited that thread?
but were afraid to ask: 
STOP!! Never post your email address in open forums. Bots can "harvest" your email! If you must share your email use a Private Message or use the 
smilie in place of the real @
Pretty Please - add it to our Events forum(s) and add to the calendar! >> 
Cold weather and oil viscosity?
- Thread starter RickB
- Start date
Share this page
Online
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
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
Online
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:
Gosh, did I seem wishy-washy there? :blush:
Pythias
Jedi Knight
Offline
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.
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
Jedi Trainee
Offline
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-
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
Jedi Trainee
Offline
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-
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-