I just found out that i can put oil cooler on my yamaha warrior, and i was wondering does the oil cooler really work, and would it be worth the money?

Thanks

 

A oil cooler diverts the motor oil through a cooling rad before re-entering the motor. So yes the oil entering the oil cooler is hotter then the oil exiting it which has to be better for the motor.
It works even better with a fan assisting the oil cooler rad but even without a fan it helps.
This guy actually measured the difference on his ATV. ne one running a oil cooler?? if so does it hel? - Kawasaki ATV Forum
Remember that the ATV will also need extra oil with a oil cooler and lines. In a way that also a plus.
Bear in mind its not necessary to have a oil cooler but it does help with heat. I had a 250 Moto4 with no oil cooler and it ran great for thousands of miles.

My 1989 350 Big Bear and 2007 350 Grizzly came stock with oil coolers and they have the same 348 motor. Not sure but the 350 raptor may have a oil cooler now and it has the same motor.

Here how they work on a motorcycle, same principals on all air cooled motor.