Honda FourTrax Foreman Rubicon TRX500FA5 2019 Owner's Manual page 162

Coolant
Increasing the concentration of antifreeze is not recommended
because it decreases cooling system performance. Higher
concentrations of antifreeze (up to 60%) should only be used to
provide additional protection against freezing. Check the cooling
system frequently during freezing weather.
Checking & Adding Coolant
Refer to Safety Precautions on page 119.
Check the engine coolant level each day before operating your ATV
and add if needed.
LEFT FRONT
(1)
(2)
(3)
(1) reserve tank
(2) UPPER level mark
1. Make sure the vehicle is on level ground.
2. With the engine at normal operating temperature, check the
coolant level in the reserve tank (1). It should be between the
UPPER (2) and LOWER (3) level marks.
If the reserve tank is empty, or if coolant loss is excessive, check
for leaks and see your dealer for repair.
152 Servicing Your Honda
(3) LOWER level mark