You might try a search on this subject, it's been cover before you joined.
Don't quote me on this but if I remember right you can use just about any motor oil as long as you stay away from the ones that have the EC inside of a circle on the back of the container. This marks it as an enviromentally friendly oil and is not recommended. I run all brands of oil in our bikes and that includes Wal-mart brand, and we ride a CR 250, a YZ 426F, and an RM 65 and have had no trouble at all.
the EC in the circle denotes that it is energy conserving, which means that it contains an additive package that is extremely slippery.Possibley those additives can attach themselves to your clutch plates causing them to slip.
Just thought that you might want some clarification on that.
Every manual I have seen states to use a particular brand OR equivelent.Then they will give you a little info say 10w40 sj for certain temp/riding conditions.
I feel it is much more important to change the oil often and to have the right viscousity then the name brand of the oil providing that you are starting off witha decent quality or better than the bike deserves. I believe that oil contamination is more of a problem in my bike than the quality of oil breaking down so it gets changed often with cheaper stuff.
You can find plenty of info if you look in these forums and you can be better off making decisions on oil brand/quality and service intervals that will fit your conditions and budget.
Many thanks for the replies. I'm learning my way around the bike and the forum...
The Honda Owner's Manual recommends GN4 or equilavent. I've never seen that on auto oil, but a buddy at work said he'd used auto oil in his bike for years with no problem. So I picked up a bottle of the Honda GN4 oil. The back of the bottle says that the GN designation is because the oil also lubricates the transmission and it is needed because of the shearing action of the cycle gearbox and wet clutch. I'm still sort of confused about all the oil viscosity rating stuff. Many thanks for the assistance. Great site! I'm sure I'll have many more questions to come...
Take a look at oils designed for heavy duty trucks if gear meshing issues cause you alarm. Most heavy duty trucks will have a lot of gear driven engine accesories, air compressors, injection pumps, cams, power steering units are rarely driven by chain or belt. As for the clutch I am more worried about the particles of clutch plates being sheared off and floating in the oil then the oil itself breaking down.