Bonneville America Forums Forums Technical Forums General Tech 20-50 W oil vs 10-40 in New England

I've been using Motul 5100 Ester 20-50 synthetic blend, since break in period, $55 vs dealer $ 100 oil change price. Question in the cold weather 50 to 70 degrees: New England early spring and late fall, is 10-40 a better viscosity of oil or no difference???

I just tried the 5w-40 Rotella from wal mart. Living in Buffalo, it seems to turn over easier in the cold weather to start. I have no real knowledge to say if it is better or worse, just seems better. I am thinking the cold viscosity of 5 is better for the northeast, and being a synthetic, 40 shouldn't really breakdown at temperature. Experts should chime in to correct me please.
jeff

I run 10W40 Mobile-1 MX4T year round.
It gets to around 117 degrees in the summer.

In the long run, I don't expect choosing one over the other will affect engine life at any perceptible level, even to run a high mileage dual test and to pull down the engines and mic them. The 5W or 10Ws will like the cold a little better than a 20W.

If I'm not mistaken, there are people around here running the 40w in big bores, likely with higher heat issues than stock, who get good oil analysis results that aren't showing thermal break down.

Just my opinion -- As long as we keep the oil reasonably clean, let's say with a 3 to 5,000 mile change interval, and use one of the four or five oils mentioned around this site, I believe "it's all good."

I don't know about Motul oils, but for Amsoil here is the difference

Pour Point (ASTM D-97)
10W-40 = -51 degrees F
20W-50 = -38 degrees F

Flash Point (ASTM D-92)
10W-40 = 453 degrees F
20W-50 = 464 degrees F

As you can see there isn't all that big of a difference.

Tom

i run 20 50 all the time

Frank

Quote:

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I run 20w-50 precisely for those -37 degree days in Daytona Beach.

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With global warming and such you just never know when it might come in handy.

Global warming is what chickens do.