Quote:
Originally Posted by serialk11r
I'm pretty sure that's the absolute minimum temperature your car is guaranteed to start. From what I understand, even summer temperatures are too low for the oil to flow well, and the majority of wear occurs on startup and when the engine is still cold, and that doesn't mean cold to the human body  |
Guaranteed based on the definitions. Unfortunately the SAE viscosity grading system does not have a "grade" to specify performance at lower temperatures than those associated with 0W. However that does not prevent formulation of viscosity values lower than the maximum for the grade's temperature definitions.
Butane is added to gasoline in winter, to assist low temperature starting. Butane has a flash point of -60C. So as long as the front end of the fuel can vapourize(has a low IBP), it has an appropriate distillation curve, the engine oil is thin enough to allow pumping and fast enough cranking to meet minimum start rpm, and the battery retains enough amps an engine can be started at temperatures lower than -35. Actually its usually battery cranking amps loss with temperature decrease that has the greater impact on starting ability.
".....even summer temperatures are too low for the oil to flow well, and the majority of wear occurs on startup and when the engine is still cold..."
Correct to a point but more appropriately stated as: there are benefits from using low viscosity multigrade oils even in summer.