2006 Honda TRX680 Rincon Factory Service Manual, Page 95Get this manual
MAINTENANCE DIFFERENTIAL OIL LEVEL CHECK Place the vehicle on level surfaceRemove the oil filler capCheck that the oil level is up to the lower edge of the oil filler holeCheck for leaks if the oil level is lowPour the oil through the filler hole until it reaches the lower edge of the holeRECOMMENDED OIL: Hypoid gear oil SAE #80
Coat new O-ring with grease and install it into the oil filler cap grooveInstall the oil filler cap and tighten itTORQUE: 12 (1.2 kgf m, Ibf-fft)