0w40 mobile 1

[albertax5]

will ow40 mobile 1 make a big differance over the 5w30 for -30 celcius morning starts?

[motordavid]

One can read oil study sites, on the web, until one's hair hurts...
my vote is for 0W-40 Mobil 1, especially for cold winter morning starts.
GL,mD

[albertax5]

thanks,just confirming my thoughts....

[faz]

In Alberta weather, for cold starts, I would go to the lowest (0) rating.

I used to have an old Huyandai back in early 90s that burnt oil and I had to add oil to it once a week. Of course, it was the cheapest regular oil possible that I would put in. Well, the first time that I had to put a 'regular' 5w30 oil in a -20 celcius weather of Ottawa/Canada, and saw how that thing 'flowed' out of the bottle that was left in the car overnight (it was like pouring slushy)... I decided: 1) I needed to go synthetic and 2) would definitely use 0w40 in that kind of a climate.

[JCL]

I can confirm MD's thought that this stuff can make your head hurt, but here are some numbers for you.

The SAE J300 viscosity standard for the 0W is a result of testing the maximum viscosity at -30C
The SAE J300 viscosity standard for the 5W is a result of testing the maximum viscosity at -25C

That isn't to say that the maximum viscosity is the ideal viscosity, just that as you exceed it it is harder for the starter motor to turn the engine over. You will very quickly get a few degrees of heat into the oil, and so raise it above these temperatures. What matters is the wear during that (short) time, and the ability of the starter/battery to crank the engine fast enough for it to catch.

I would also think about the range of viscosity in the oil. A 0-40 generally has more viscosity modifiers than a 5-30, and/or a different basestock, just to get the range of viscosity standards. Too many viscosity modifiers means that the oil changes in other characteristics as well, not always to the better.

All that said, I would use a 0W-XX oil at -30C, to get the cranking speed.