Honda FOURTRAX RANCHER 2019 Owner's Manual page 146

Engine Oil & Filter
7. If the oil level is near or below the lower level mark, remove the
seat (page 124) and the tank cover assembly (page 125). Remove
the oil fill cap (5) from the front right crankcase cover and add the
specified oil into the fill cap hole, up to the upper level mark on
the dipstick.
Do not over fill.
8. Reinstall the oil fill cap and dipstick.
9. Install the tank cover assembly.
10. Install the seat.
11. Install the oil check lid.
NOTICE
Running the engine with an improper oil level can cause serious
engine damage.
RIGHT SIDE
136 Servicing Your Honda
(5) oil fill cap
(5)