Bob
You only quoted a small portion of what I was talking about.....
"Molecule . a quantity of a substance, the weight of which, measured in any chosen unit, is numerically equal to the molecular weight; gram molecule.
any very small particle."
The size of the molecule will determine the viscosity.....
And like I said...5W30 stands for 5 weight winter
oil at 32*degrees and 30 weight molecule at 212*degrees .....
So in the racing world....when Mobil came out with their 0W50 racing
oil with 1800 ppm of ZDDP......many of us changed over to it from SCCA, NASCAR, to INDY Car, because it flowed on initial start up and the 50 weight molecule worked great at the high temperatures....on our cams and crankshaft.
BTW....if you have ever seen 50 weight
oil at temperature flowing......it looks like Black Water......