Can you prove it runs hotter?
The temperature range it runs in is wider, true, but I'm not so certain it runs significantly hotter. I can even see it running too cool if you're riding secondary roads or canyons... maybe in stop and go city traffic yes...
(one of my other bikes is an air/oil cooled DR650, which under most circumstances runs too cool rather than too hot. People measured the oil hardly getting over 90 degrees even in the summer. People cover the oil cooler in the winter)
Well, I can't prove anything, but my leg and butt know to a moral certitude that a Scrambler 1100 runs hotter than a FJ09 or Aprila Mana 850 which are both liquid cooled. So I'm satisfied that for my purposes, a premium motor oil designed for an air cooled engine will likely perform better in my Scrambler than one designed for either all engines or liquid cooled engine. And the FJ09 and Mana will get the other oil (which costs less too).
I'm certainly willing to accept that DR650's run cool but that seems to be an exception among air cooled motorcycle engines. There seems to be almost unanimous agreement among writers discussing the subject that air cooled engines run hotter than liquid cooled engines. This
Understand Motorcycle Oil @ MotorCycleAnchor.COM is pretty typical:
"Motorcycles Engines are Special
In most motorcycle engines, those same engine surfaces generally move much faster than they do in car and truck engines, conventionally twice to ten times as fast, due to difference in RPM ranges, stroke lengths, stroke speeds (i.e. - piston speed), etcetera. .Additionally, most modern street-oriented motorcycles have a "wet clutch", which means that the clutch plates also sit in the same oil that the rest of the engine uses to lubricate itself. Most also have the transmission also sharing this same oil.
Throw in the fact that some motorcycles are still oil-air cooled (which causes the oil to run 1.5 to 3 times hotter than a water-cooled engine). These four differences (speed, clutch exposure, transmission exposure and oil temp) are the grounds for the basic differences between formulations of motorcycle oils and car oils."
While oil in an oil/air cooled engine being 1.5 to 3 times hotter sounds extreme to me, the writer's sources are listed at the end of the article, so I guess if I cared, I could look them up.
