I had a 2000, 200cc MXC and bought a 2003, 200cc MXC this past Sept. My son races a SX 125. We both run hare scrambles. We have tried several different brands of oil and have settled on the Maxima MTL Fluid, 2-cycle transmission lube, ClutchSaver Formula. We use the Maxima Formula K2 Racing 2-cycle, High RPM Racing Rormula premix. Log onto www.Maxima.com for detailed info on these products. Motorex oils are great too but sometime hard to get.
I've noticed the biggest difference using motorex as far as smoothest shifting goes but like the post before me I find it harder to come by. I've tried all kinds of higher priced "motorcycle shop" oils but after surfing through all the post's thought I'd try something different. Call me crazy but I've been using plain ole Quaker State 10w40 for the past 5 or 6 oil changes. I notice no difference in shifting or clutch performance. The oil looks pretty clean at changes too. At a little over a buck a quart by the case I can change oil very often without the :moon: pucker factor.