Carguide, a Canadian magazine, posted the following winter maintenance tip in their October 2005 issue:
quote:So I shot them a quick e-mail, which they published in the February 2006 issue:
Use a low-viscosity oil, ideally a 5-W-30 [sic], which is thinner or runs more freely at low temperatures, and thickens somewhat as the engine (and oil) heats.
Please note that oil thins as temperatures increase (Winter Prep, Oct. '05). Also, a more ideal motor oil than 5W-30 for most Canadian winters is a 0W-20, 0W-30, or 0W-40, depending on manufacturer recommendations.
quote:I'm pretty sure they're standing by their assertion that the "W" means that the oil thickens as it warms up!
Raw oil thins as temperatures rise. In order to protect an engine at startup, the oil needs to be thinner when cold so it flows freely. Viscosity modifiers are added to the base stock to make the oil flow better when cold, without making it too thin when hot.