At 40c +/- temps...... 10w50 should be ok. Coming on summertime in Oz.
Manual says 10w-40.. The rear drive oil only 90w above 41C. Putting 140w multi-vis in the rear drive may cause issues. Just sayin..You're right. I missed that. My reading comprehension doesn't allows comprehend like it used to.
I would normally run 10w40 and I mixed 75w90 with 75w140 so I am guess it ends up being 110 something.Thicker oil there only causes more friction and heat, making things worse man. Stick what it's recommended. Factory says 75/90 for a reason . On the engine oil, if you're not tracking the bike or running it super hard, same thing. Stick to the recommended viscosity... but I'd definitely use a fully synthetic oil, which lasts longer and has less viscosity breakdown. Good luck.
Hi Everyone from down under, about to head off on my first East-West ride on a GTR1400, starting in the North West of West Australia and heading first to the War Birds Air Show in Temora NSW with our final destination will be Southern most point of Tasmania. ....