You can, but if it is not water-cooled then it will not lubricate correctly since an air-cooled engine runs at nearly or greater than the temperature of a water-cooled engine.
if you have to mix oil with the gas its 2 stroke or cycle and if you have to change the oil its a 4 stroke or cycle
How do you put oil in Kawasaki 250 four wheeler
NO
drain you oil and flush it out
20W-50
10w-40 ATV or motorcycle oil should be fine.
A 10w40 oil with an American Petroleum Institute or API rating of SF or SG.
This question is not answerable because we do not know what model your four wheeler is. Try consulting the owner's manual or ask this question again with the model number/name.
The oil you use in a four-wheeler is exactly the same as you use in a vehicle. If your four-wheeler is air cooled I highly recommend you use a 100% Synthetic oil in SAE 10w30 weight. If it is water cooled use either Synthetic or Conventional oil.
Detergent! Do not use non-detergent oil.
motorcycle 10W40
yamalube its good stuff factory recommended