How do I change the oil in champion 40 petrol mower ?

90% of lawn mowers change the oil from the underbody were the blades are, take the sparkplug cover off for saftey first , turn the lawnmower on its side, clean the underbody, look for a allen key nut in the underbody, unscrew it,and the old oil will drain out, empty it, put the bolt back in tight, refill the new oil, into the oil cap ,test it with the dip stick,

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September 2016