Exact machineDo not buy parts from a broad answer.
Do not treat any coolant, fan, thermostat, hose, cap, radiator, fuse, sensor, or service kit as the right fit until the exact machine, year, trim, cooling-system layout, and manual or catalog details are confirmed.
Safety boundaryStop when the answer stops being enough.
Stop immediately and get hands-on help if coolant is boiling, steam is present, warning lights continue after cooling, coolant is leaking, the fan wiring looks damaged, or the machine could leave you stranded.
Deeper pathUTV overheating guide
This answer links into the deeper guide before Traxer asks for the machine details that make the next step useful.
Read the guideWhy it stops hereHelpful first checks without pretending certainty.
Traxer reviewed this against the related overheating guide and coolant boundary. It gives first overheating safety checks, not a final cooling-system diagnosis or final coolant or parts answer.