And, car engines have similar pistons, cams, gears, chains, etc -- run for hundreds of thousands of miles, often get scant attention (maintenence-wise), and seem to get along quite well with "regular motor oil"?
Of course -- with an engine, reportedly, as frail as the FJR's -- one can't be too careful!
And, as hard as most riders push these puppies -- y'all run at 75% or better? right? it'd be "cheap insurance" to just run the best. Ahh, but there's the rub....
Those car engines running on GF4 oils with the starburst symbol are NOT running wet clutches like most motorcycle engines.
I'll have to check further but I believe that there are several 10W40 oils that are GF4 approved and have the starburst symbol for gasoline engines...meaning that they have the friction modifiers in them.
You cannot just lump all engines together and assume that what works well for one will work well for all of them. It takes a more detailed understanding of how the engine is designed and what content is in the engine to determine what oils might or might not be appropriate.
We mentioned the wet clutch already. You do NOT want any normal, gasoline engine or automotive oil in the FJR due to the friction modifiers.
Most all modern car engines have roller tappets, no distributor gears driving the oil pump, roller rockers, etc... All items designed to minimize the dependency on the anti-wear properties of the oil. This allows the anti-wear ZDP additive concentration to be reduced in normal gasoline engine oils to minimize the cat converter poisoning from the phosphorus in the ZDP.
On the converse the FJR engine has 16 rubbing element, direct acting tappets and fairly radical cam profiles that do need higher levels of the ZDP antiwear additives to ensure minimum wear and long mileage survival. Not that the FJR engine is fragile...it just has design features that make "normal" oils for gasoline engines (in cars) not appropriate as stated above.
Forget all the concern over 10W40 or 20W40 or spending mega dollars for specialty botique oils. Buy the 15W40 Rotella/Delo/Delvac oils marketed as "diesel oils" and forget about it. The so called diesel oils have much higher levels of the ZDP antiwear additives and no friction modifiers to cause your wet clutch to slip with time and miles.
And if you know nothing about oil please stop spreading bad information.
