08-28-2021, 01:56 AM
My two bits, just remember the following : Honda bikes should never run on modern, full synthetic. Summer or winter temps have nothing to do with it.
From somewhere on the internet (I kept it in my files without url):
Car oils have been used up to 1998 as the base for most motorcycle oils. But as the technology in cars evolved, the oils were modified to meet those modern needs. As a result, additives were added and friction modifiers were blended with the oil. Although these modifications were positive for use in cars, they were damaging to motorcycles. This was especially the case with motorcycle gearboxes and clutches. Unlike with cars, motorcycles don’t use a separate oil for the gearbox, causing the clutches to slip due to the friction modifiers. It also could attribute to gearbox pitting (localised corrosion and the formation of micro-cracks). Oil in motorcycles and scooters is required to run under more intense conditions than in cars because it has to endure hotter temperatures as well as higher engine speed and a greater power density. These circumstances subject the oil to significant operating stress.
Our CB requires JASO MA or JASO MA2 oil.
I know you asked about viscosity, but I think this question is secondary to the issue raised above. No doubt, if your bike sees an extreme temperature range between winter and summer (more than 40 degrees ?) you have to address this problem. On the other hand Japan has extreme weather zones, and the user manual states 10W-30 as a house number.
From somewhere on the internet (I kept it in my files without url):
Car oils have been used up to 1998 as the base for most motorcycle oils. But as the technology in cars evolved, the oils were modified to meet those modern needs. As a result, additives were added and friction modifiers were blended with the oil. Although these modifications were positive for use in cars, they were damaging to motorcycles. This was especially the case with motorcycle gearboxes and clutches. Unlike with cars, motorcycles don’t use a separate oil for the gearbox, causing the clutches to slip due to the friction modifiers. It also could attribute to gearbox pitting (localised corrosion and the formation of micro-cracks). Oil in motorcycles and scooters is required to run under more intense conditions than in cars because it has to endure hotter temperatures as well as higher engine speed and a greater power density. These circumstances subject the oil to significant operating stress.
Our CB requires JASO MA or JASO MA2 oil.
I know you asked about viscosity, but I think this question is secondary to the issue raised above. No doubt, if your bike sees an extreme temperature range between winter and summer (more than 40 degrees ?) you have to address this problem. On the other hand Japan has extreme weather zones, and the user manual states 10W-30 as a house number.