theputz

I have been reading through the other fluid posts but don

SpitfireS

Is the car parked outside?
Is it -20C when you start it?

I would get a 0W-30 for the engine (summer/winter, its ok to use it )
Amsoil makes a 0W-30.
Mobil1 is available in 0W-30 (not the EP type though)
German Castrol is almost a 40 weight, but is called a 0W-30.
I don't know if you can get the Shell Helix Ultra X 0W-30.

Again, Amsoil 75W-110 for the diff.
Or, Castrol 75W-140.
The pourpoint of LE-1605 (SAE 110) is -24C so it would still flow.
Even in cold weather the diff will reach operating temp, remember that.

For the transmission... I donno.
MTF-III works ok.
So does the GMSFM gear oil.
I don't know how both perform at -20C though.
They are both probably a 75W'ish-90'ish gear oil, so they both will flow at -20C.
Don't idle the engine to operating temp, start - 10 seconds - drive is best.
That way you warm up everything the fastest and with driving the gearbox' oil pump is pumping oil.
Parked, at idle in neutral it isn't.
That's more important IMO.

I hope this helps you.

theputz

the car is parked in the basement of my building so its heated. It sees those temperatures only when it goes up the mountain snowboarding so a couple times a week.