I have it narrowed down to these 2 oils to use in my 2006 1200 Harley Sportster. I ride the bike all winter and these cold starts I have been doing with the 20w50 dino "360" oil sound horrible. The engine clanks a bunch on start up and does not want to run. I'm going to change the oil to eather M1 15w50 or M1 20w50 V-Twin. Which would be the better oil for very cold starts? I keep thinking the V-Twin is the better Motorcycle oil because it is made specificly for them while the M1 15w50 is more for cars. Will it make much difference what I put in the engine? I want good wear protection and good start up flow/protection in cold weather. Thanks again!!!!