Honda FourTrax Rubicon TRX520FA5 2020 Owner's Manual page 155

Changing Engine Oil & Filter
Refer to Safety Precautions on page 121.
Your ATV's oil filter has very specific performance requirements. Use
a new Honda Genuine oil filter specified for your model or a filter of
equal quality.
NOTICE
Using the wrong oil filter may result in leaks or engine damage.
This procedure requires mechanical skill and professional tools such
as a torque wrench as well as a means for disposing of the drained
fluid (page 214). If you do not have the skills or the tools, see your
dealer.
Change the oil with the engine warm to assure complete and rapid
draining.
Drain the Engine Oil:
1. With the ATV on the level ground, remove the seat (page 132)
and the tank cover assembly (page 134), and then remove the
engine oil fill cap from the front right crankcase cover.
2. Place an oil drain pan under the crankcase and remove the
engine oil drain bolt (1) and sealing washer (2).
UNDER ENGINE
(1) engine oil drain bolt
(2)
(1)
Engine Oil & Filter
(2) sealing washer
Servicing Your Honda 145