Erm, from what I remember, yes it would seem a better idea to drain and then refill (using the same oil if you're sure it's new, I guess).
Not sure what hyper-pressure would do to the bearing(s), but I'd NOT want hot surplus oil being vented so close to my rear tyre.
Not sure what hyper-pressure would do to the bearing(s), but I'd NOT want hot surplus oil being vented so close to my rear tyre.