Previous OCI ran M1 10w40 4T in the Rex, granted not winding it out other than now and then in street riding, 4,603 miles didn't use any oil. Current fill is M1 20w50 V-Twin, just over 4,800 miles with the last 1,400 in 5 days a week and a half ago running around southwestern Colorado doing lots of mountains and hasn't used any either. Really pleased with the JE piston install I did spring of 2018, sealed up well on the rings. Going to take it to a bit over 5,000 miles and send off a sample when I change it. Debating (flipping a coin maybe?) whether continue with the 20w50 or back to the 10w40 4T. Engine seems to run a bit warmer with the 20w50 in hotter temps at higher elevation (ZX9 gauges installed which have a temp gauge). I recall that as well from running another brand 20w50 3 or 4 years ago vs the Rotella T5 15w40 I ran before that.