quicksilver 2cycle oil....make sure it is API-TC rated..i believe you have the 720 engine correct...if so then you dont ned synthetic you can use mineral oil
use BRP mineral oil in your 587 rotax. A gallon is about 35 bucs. You will need to clean out the tank, replace oil filter and the two small Tygon 3/32" oil injector spigot lines (Weedeater). 14" will do it, 8" + 6" long.