(Referring to oil weights and oil viscosity...feel free to correct me on anything that's off base)
"The second number in a multigrade oil means that oil will not THIN more than that weight at operating temperature (i.e. 100 C). It does NOT mean that it's thicker at operating temperature than the first number. It's really quite simple. Did you even see the cSt ratings for the PP at temperatures? The polymers coil up so that it will flow better at low temperature. But they lengthen to keep it from *thinning too much at higher temperatures*, not to make it get "thicker" than the first number. There is a difference. It's not making it get thicker, it's keeping it from getting too thin, get it?
So what does this mean? Yes, 5W-20 oil will flow like a 5W oil when cold, and will not thin any more than a 20W oil when hot. But it's cSt reading (i.e. viscosity) is much, MUCH higher when cold than when hot."
"The second number in a multigrade oil means that oil will not THIN more than that weight at operating temperature (i.e. 100 C). It does NOT mean that it's thicker at operating temperature than the first number. It's really quite simple. Did you even see the cSt ratings for the PP at temperatures? The polymers coil up so that it will flow better at low temperature. But they lengthen to keep it from *thinning too much at higher temperatures*, not to make it get "thicker" than the first number. There is a difference. It's not making it get thicker, it's keeping it from getting too thin, get it?
So what does this mean? Yes, 5W-20 oil will flow like a 5W oil when cold, and will not thin any more than a 20W oil when hot. But it's cSt reading (i.e. viscosity) is much, MUCH higher when cold than when hot."