Quattro Pete But the viscosity grades don't seem to overlap. Am I supposed to switch from 0w-30 to 5w-30 just because the outside temp rose from 0F to 20F? That's what I don't get. [/quote said:Yeah, especially if the snowblower is garage kept. I would think the 0 weight would be for cold outside starting, and you wouldn't have that concern if it's ten below while you're blowing snow all over the place with a warmed engine.