Is this a two stroke machine? if so the oil is in the fuel,not in the crankcase, if the oil is coming from the muffler it is probably because you are putting too much oil in the fuel, if its a four stroke ( Honda ) engine contact your local horticultural dealer, these do have oil in the sump, Stihl 4 mix machines do not have oil in the sump, they also run a fuel oil mix.
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