Originally Posted by billdonna
At start-up you are not at working temp
. My understanding is that the majority of engine wear occurs at start-up and during warm-up for the average Joe. So it is important to pump oil from the sump to the upper reaches of the engine ASAP. Thin oil moves thru the engine faster.
So when there is snow on the ground, would you rather be pumping STP viscosity oil or thin oil to lube your cam?
Here's a link to explain it all..
Oil performance at low temperatures is determined by the number before W and the linked article mostly deals with it.