hi my buddy just bought a 1982 maxim xj750 the previous owner told him it would need an oil change soon so were getting ready to change the oil but do not know what weight of oil was recommened by the factory. the motor has recently been rebuild with all new parts and i know not to use automotive oil in a motorcycle they have different additive packages. We got a filter from the local yamaha dealership but the person working the parts counter didnt know what weight of oil to run it in. thanks in advance