[kartgreen]

I use an oil from England , Morris Classic , it's made for older motorcycles such as our bikes . Our Hondas have the spin filter which is made to coral the larger pieces of contamination circulating in the oiling system . Modern oils have detergent agents added to breakdown these larger contaminations to a much smaller size which are then removed in a normal oil filter . This allows the oil to last longer , re: less contamination of the oil over extended miles . Morris also contains a zink additive.
As everyone else has stated at the least use a diesel rated oil such as Shell Rotella . Be aware the Rotella comes in different formulas . If you can't find a low / non detergent ,zink containing oil at your local parts store look for a Tractor Supply or a farm/ tractor store and you should find what you need .
Morris does have a distributor in Virgina that will ship by the case . I use 30 wt. as well as 40wt. and they will mix a case to siut your needs . The big thing to remember is modern chemisty doesn't mix well with the old technology of our bikes . AS BTL stated change oil often , I change all of mine yearly and several of them don't see 30/40 miles a year .