I use Total 10W-50.
Recommended by cfmoto.
The 50 comes into play at high ambient temps.
This month the temps were out of control, 44C/112F in shade, 60+ on the road/trails.
We were on vacation, we did 700kms, rode the machine everyday, fully loaded 2up, pretty hard on pavement and trails, the fan was at full tilt constantly, the machine never over heated, 4 bars for a few seconds then 3. On one uphill trail low gear low speed again fully loaded it could not cool down to 3 bars, it held 4 bars on the gauge and, i swear, you could cook something with the heat that the machine was giving of.
When i got back the valves sounded a bit off, they were noisy, not clicky but noisy. (never done them prior, skipped them at first service).
I did a full service and inspection (1000kms on the odo), all fluids (except coolant) and valve adjustment (front cylinder is a major PITA btw).
Oil had become a bit brown, viscosity was good.
The machine is back at perfect working order, checked all bolts nothing loose.
Oil is cheap, if you ride the machine hard, change the oil more often.