2006 Honda TRX680 Rincon Factory Service Manual, Page 90Get this manual
MAINTENANCE The engine contains sufficient amount of oil if the oil level is between the upper and lower level marks on the dipstick
DIPSTICK
UPPER LEVEL LOWER LEVEL If the oil level is near or below the lower level mark, remove the oil filler cap cover and oil filter cap, and add the recommended engine oil up to the upper level markRECOMMENDED ENGINE OIL: Pro Honda GN4 or HP4 (without molybdenum additives) 4-stroke oil (U.S.Aand Canada), or Honda 4-stroke oil (Canada only), or an equivalent motorcycle oil API service classification: SG or higher (except oils labeled as energy conserving on the circular API service label) JASO 903 standard: MA Viscosity; SAE 10W-40, 5W-30 NOTE: Other viscosities shown in the chart may be used when the average temperature in your riding area is within the indicated rangeReinstall the oil filler cap, oil filler cap cover and dipstick