Hello I live in Italy. My question is this: to change the oil I take the allen bolt near the gear pedal also the bolt under the engeno and the the little cover screw that is also for cecking the valve. My problem is I always get 500 ml out and when I put the new one it takes the same amount. I can not take the streiner bolt (if that is the right name ) out it seems to be welded and now the head is starting to get rounded. Is that why I can not get all the oil out and what should I do for that bolt?