My 2008 Tomos Streetmate is Type F stock, but the shop manual says two options are available. Mercon ATF will allow the bike to shift into second gear a little sooner, while 10W-30 motor oil will hold first gear longer for better acceleration. It also says 10W-30 isn't recommended in colder climates because of harder starting. I've only used Mercon becuase I'm more certain of the quality. Type F fluid is tough to find and when you can it's usually a bargain brand I've never heard of.