the primary/trans share same fluid. holds 1 quart to fill from fully drained. drain plug is under primary, has 5/8th head meaning 5/8th box wrench or socket removes it. is same drain plug as installed from factory in swingarm. the swingarm plug is for engine oil. personally what i would do is drain the primary fluid, let it drain for at least 20 minutes. you'll find small amount of shavings on plug magnet. clean off and make sure o-ring on plug is in good shape. if not replace it as it forms the sealing surface for plug to primary. i use either bel-ray #80 trans fluid, motul synthese trans fluid, or any 20-50 wt. motorcyle oil such as castrol act-evo, mobil v-twin, they're all primary wet clutch approved and excellent. everyone has their own preference. amsoil also pricey but excellent. refill primary thru upper or lower windows, doesn't matter. check primary chain adjustment while you're at it. specs for same listed on this site but amount of freeplay or slop is 3/8th to 1/2 inch. then go back and do the clutch cable complete adjustment as i described earlier and you should find alot of improvement on shifting. like sportsters, i've found that when the bike and the fluids are cold, that buells can be a tad notchy shifting and take a bit of coaxing to get into neutral when idling in first gear. with correct adjustment and fluid they shift nicely. IMO