For Minus 30 temperature Mobil 1 0W30 or 5W30.

Without knowing what car/truck you have one could say 5W30..! However to be more accurate, would you please tell us what vehicle you plan to do the oil change on..? Or, you could check

I'd use the 0W30. Once the oil warms to operating temperature, it will be almost the same as the 5W30, and when it is cold it will flow much better.

Ed

Denny B wrote:

1981 Ford Fairmont 6cyl that has been well maintained in a milder climate but is now driven in a much colder climate.

I am the original owner of this vehicle.

Thanks Denny

However to be

Does the weight make a difference in just STARTING a car? The lower weight would mainly reduce damage from extremely cold starts.

If it is an 1981 Farimont, it is likely that the seals are already leaking. I think the idea that synthetic oil can casue problems with seals and gasket is overblown. However, if you are really worried Mobil now has a "high mileage" formula syntehtic blend oil that claims to condition seals to reduce leakage.

References:

- I know Amsoil, but theycan't always be wrong Ed

0w30 I live in northern Ontario In most older trucks of your vintage we are putting in 0w30. We have three pugs to plug in at night around here, or it wont start. Drew