2008 Arctic Cat ThunderCat ATV Service Manual, Page 16Get this manual
6Install the engine drain plug and tighten to 16 ft-lbPour the specified amount of the recommended oil in the filler holeInstall the oil level stickfiller plug ! CAUTION
Any oil used in place of the recommended oil could cause serious engine damageDo not use oils which contain graphite or molybdenum additivesThese oils can adversely affect clutch operationAlso, not recommended are racing, vegetable, non-detergent, and castor-based oils
7Start the engine (while the ATV is outside on level ground) and allow it to idle for few minutes8Turn the engine off and wait approximately one minute9Remove the oil level stick and wipe it with clean cloth10Install the oil level stick and thread it into the engine case11Remove the oil level stick; the engine oil level should be above the illustrated "L" mark but not higher than the illustrated "F" mark