I have a qj xtreme commando 100cc atv, on top of the motor on the kick start side at the rear there is a finger **** which screws into the motor and has rubber gasket but no dipstick. I am trying to find out if this is a oil reservoir for the chain. and what kind of oil I should use. Under the seat is the bottle that holds the 2 stroke oil which injects into the carb, but I am confused about what this maybe. Any help would be appreciated.