At start-up you are not at working temp
Originally Posted by genka
OK, I'll ask a question that's been bothering me for a while. The oils with the low number after the "W" are recommended for cooler ambient temperatures. Why do the ambient temperatures matter if the working temperature inside the engine is much higher?
. 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..