Hi guy.s i need to change my gearoil what do i get?Any suggestions is it 10w 40? and from what i see it has a little black plastic pipe on top of the engines cover andta 13mm bolt underneath it.so i recon that must be the drain bolt correct for the old gear oil to drain out.And then add the new gear oil from the top black plastic pipe.which if i pull comes out.i am i correct?