gear box info
 

I have a Sunl SLGK 250cc and im currently replacing the clutch. During this process I would like to change the fluid in the gear box. Question: #1 Does this need to be done? #2 If so, what DO YOU ADD? (GEAR FLUID, TRANS FLUID MOTOR OIL) Any help would be great.

I'm assuming the CN250 gearboxes are typically separate from the engine like the gy6 ones are, however I'm assuming your talking about the final gear case (is that what it's called) directly behind the clutch. You don't need to open that to replace the oil, and yes, you use gearbox oil. On my gy6, there are two bolts that are a little bigger than the ones around them, and they are around where the clutch is. Just google "CN250 gear oil" and you should find something. For the gy6 it is recommended to use 80w90, but I don't know about the CN250s...
Now if you're talking about the physical gearbox, I think you just pop it off the final output shaft and pop I open and add lube. Because I have no clue how much different the 250s are from the 150s I can't say anything definite, but here's what I learned after diving into my Gy6's cvt last weekend :)