If its an oil injected motor there is a tank that holds the mixing oil if its just a straight carburated motor the oil mixes with the gas in a can then put it in the gas tank.
A stock Yamaha Banshee will go 77.7mph
fast
75-80mph
about 70 to 80mph
faster then your mom eating donuts
a 350 twin banshee can go up to 120 with mods it all depends
Stock gearing out of crate approx 72 mph
A stock Yamaha Banshee tops out around 72.8 mph depending on the machine and factoring in wind and friction drag from chain,wheel bearings Ect... A Fully ported and polished banshee with absoultely everything aftermarket will go up to 120 mph (like my banshee) 420cc . 540cc, 720cc , and 900 cc triple cylinder BANSHEE ENGINES can reach speeds of 200 MPH but are normally used in sand dunes/drag racing not really for the trails or public roads...
faster than you can get 1 off from beatin off, hahahahahahahahahaha CANT GET NONE
I have a 01 Yamaha yz80 it went 55 to 60 without performance parts and. I got it to go 70mph with performance parts!!! Fast enough to scare you.
The fastest stock, production atv is either the Yamaha 350 Banshee or the Suzuki Quadzilla but this is highly debated. Modified or custom atv's can go faster.
Regular fuel will do fine but a higher octane is always better. As far as oil, you can't go wrong with the Yamaha brand.