My info was not taken from any website, that is data I researched before Al Gore invented the internet!!
Multi weight oils can ACT like different weight oils at different temperatures, but how?
Heat up candle wax, what happens, it gets thinner!!
Heat up cooking oil, it gets thinner!
Cool off diesel oil, it will get thicker!
Just the opposite of what you want for engine protection.
Multi weight oil (example,5W-30) is a single weight oil with a temperature sensitive modifier that can increase base viscosity of 5W up to 30 as the temperature increases. Great for water cooled engines, for which it was developed.
But, the modifier can only modify up to a certain temperature.
Air cooled engines operate at higher temperatures than water cooled engines.
Above that temperature, the modifier fails to modify, the oil reverts back to 5W.
Exactly what you do not want!!
Think of the modifier as a long chain plastic molecule (which I think it is).
The plastic weakens above its functional temperature. The viscosity drops.
I ain't putting 5W, 10W, or 15W oil in any air cooled engine that will be used at normal load requirements.
Maybe, when and if I move back north, I will change my beliefs.
