"Whew"...loooooong story,Street
You might want to go to the topic of LUBRICATION on the forum main page...click on that and scroll down to the "Donnie on Oil" thread.
There in post#1,Wright provided a link that contains (among other things) a 3 part AIM article on oils by Donnie Peterson explaining just about any & everything you'll ever really want/need to know about the stuff...and the bottom line is/was...15w50 Mobil 1 rated #1 (due to additives etc) over 10 other top synth. oils (mostly 20w50 weights) tested...with no difference in oils labeled CAR or CYCLE this side of the 40 weights (less than 50 weights) that you would'nt want to be putting in your Harley anyhow
Lots of good reading

have fun !!!