I just noticed that Tractor supply now has Mystic synthetic blend 15W50 for diesel engines. It seems to me this might make a great motorcycle oil. The price was close to $20 a gallon.
I know a lot of HD riders here in Wisconsin that use this oil. My old 96 softail, now owned by another family member is running on this oil. Bike and owner are very happy with it.
Now that you mention it, it does seem like it was two gallons. In that case it seems like a good deal. I was hoping to find info on the high temperature/high shear of the oil at the web site but it was not listed.
I am using Schaeffers 5W40 in my Guzzi now and was thinking this oil might be even better in hot weather.