Fazer oil change

[Exupnut]

If u dont wanna use yamaha yamalube u could always try mumma's mummalube... Probably cheaper and more enjoyable :-)

[schlumpf]

I'm using 10w50 full synthetic with JASO specification for 10 years without any problems.
My personal guess is that you will hardly notice any difference whatever oil you use within the usual lifetime and use of your engine. Even if some bearings suffer you will not recognize it unless you disassemble the engine and inspect the details. If used "normal". The picture might be different under extreme conditions, temperature or race.
The difficulty is to distinguish between bad and good oils. The other day I found a writing from a guy who obviously did some decent backgound research. Maybe worth to read:
http://motorcycleinfo.calsci.com/Oils1.html
Anyway you should also be fine by sticking to the original recommendation from Yamaha.

[His Dudeness]

olive oil change it every 84,000 miles smells great

[Dcock]

im currently running some 10w40 semi-syth specific for a massey ferguson tractor in my bike. (brother is a farmer and had some left over form servicing his tractor). Have had absolutely no problems at all. (so tbh i would just go for any 10w40 semi-syth, its not like your running a superbike so dont go wasting your money) I used to put in rock-oil from my local shop, that was pretty cheap as well.