How thin is too thin?
At -40 those bearings will get mighty stiff. A synthetic grease will allow the bearings much better lubrication during the initial drive after a cold start, until the grease can warm up on it's own. I'd also lube the U-joints with a synthetic grease, and especially any and all grease fittings for the chassis.
Tie rods, ball joints, bushings, ect. don't neglect those parts.
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Also, at those brutal winter temperatures, I'd make sure I'd repack my front wheel bearings with a good quality, synthetic grease.
At -40 those bearings will get mighty stiff. A synthetic grease will allow the bearings much better lubrication during the initial drive after a cold start, until the grease can warm up on it's own. I'd also lube the U-joints with a synthetic grease, and especially any and all grease fittings for the chassis.
Tie rods, ball joints, bushings, ect. don't neglect those parts.
Ed
This will help the engine retain heat much better, and cool down slower. Zero degrees to -40, an engine starts to cool very quickly/...




