5/40 vs 15/40 vs 20/40

[Tide230]

Thread title should say 10/40, not 20/40. Can't edit title.
Yes, this is an oil question, so please, no exploding heads!
I have a new 2020 KLX230R. First oil change is due at 5 hours. I'm new to 4 stroke dirt bikes and have zero knowledge about this. I plan on frequent oil changes.

The book says 10-40. Rotella seems widely used on this forum. But T4 & T6 are not 10-40. Not sure to use a different weight or a different oil.
In Central Alabama, so the temps are not too cold in winter, but it gets pretty warm here in summer. And I'm really concerned about this given the bike is air cooled.

Hoping someone here can guide me without heads exploding about yet another oil questions.

Thanks for reading.

[PawPaw]

Just be sure what ever you use is wet clutch rated or you will fry your clutch.
I do use Rotella T6 and it is good, but others will debate that. Everyone has their own experiences and preferences.

Paw Paw

[cowboyona426]

There should be a chart in the manual that shows which oil weights are recommended depending on temperatures. Myself I wouldn't worry too much about the smaller number, but I wouldn't run a 50 weight oil in an engine that wants 40 weight.