10w30 vs. 10w40

[Boonetown_imp]

Is Honda 10w40 ok to run in the cb? Can I alternate between 10-30 and 10-40? Not mix.

[misterprofessionality]

Where I live it's oppressively hot 3/4 of the year, and it's very easy to get caught in gridlock traffic, so i'm a 10w40 full synthetic guy.

[peterbaron]

Where I live it's oppressively hot 3/4 of the year, and it's very easy to get caught in gridlock traffic, so i'm a 10w40 full synthetic guy.

^^+1^^

[Scotty_imp]

See the post titled "Viscosity knowledge"
I'm in SoCal and only run 10W-40. I fear it's still too thin on days like today...

[Cormanus]

Yes to both questions.

[Houtman_imp]

I use 10/40 because of the warmer weather here in NC , if you mix the two half and half you have a 10/35 , no problem with that.

[GoldOxide_imp]

Up here in the deep south Ontario Canada in -25C winter and +40C summer 10W40 appears to work just fine on the ol' air cooled CB1100. I never used 10W30 non-synth during summer. It was like water (okay, once it was used).

Ultimately I ended up using 5W40 synthetic.

[Obleo]

I posed that question a while back. Really hot in the mid- south, in the summer 10/40 and winter 10/ 30 - half and 10/40 half . The bike seems to like it .

[j3gq_imp]

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.

[Houtman_imp]

There are plenty of synthetic MOTOR CYCLE OILS perfectly fine for Honda motorcycles , just do NOT use synthetic CAR oils in our bikes !