Honda FourTrax Rancher TRX420FE1 2019 Owner's Manual page 140

Rear Final Gear Oil
1. Park your ATV on a firm, level surface.
REAR
(1)
(1) oil drain bolt
2. Place an oil drain pan under the oil drain bolt (1).
3. Remove the oil fill cap (2), O-ring, drain bolt and sealing washer.
4. After the oil has completely drained, reinstall the drain bolt with
a new sealing washer and tighten it to the specified torque:
9 lbf·ft (12 N·m , 1.2 kgf·m)
5. Remove the oil level check bolt (3) and sealing washer.
130 Servicing Your Honda
(2)
(2) oil fill cap