I have a '00 Kawasaki Vulcan 1500 Classic. It is a water cooled V-Twin. I'm trying to decide whether to run M1 10W-40 or 20W-50 motorcycle oil. It is a water cooled V-Twin. I have been running 10W-40 but thought I might go with the 20W-50 since I only ride it in warm weather and have a heavy wrist. Comments?????