How about in hot weather conditions? Sometimes 100°F+ ambient, usually in the 80°Fs, never below the occasional and rare 55°F, low-humidity, Mediterranean climate. Oftentimes spirited canyon riding.

I'm concerned the Kawasaki-recommended 10W-40 oil may not hold up to such conditions in a bike with a 16k rpm redline. Especially considering some bikes have been experiencing low-mileage catastrophic engine failures which seem related to heat.

The manual reads, "Although 10W-40 engine oil is the recommended oil for most conditions, the oil viscosity may need to be changed to accommodate atmospheric conditions in your riding area".

Thinking to go with Motul 300V Road Racing synthetic 15W-50. Anyone have good reason why not to?

 

I've been running 20W-50 since the first oil change, but 100° is a nice day where I live and my bikes never see temps in the 30's