KWA KP8 gas airsoft gun?

Green gas is propane with silicon lube. Unless you live next to a place that sells green gas, you will have to buy it off of websites which will cost a fortune in the long run. Best bet is to get a propane adapter and some liquid silicon lube. The propane adapter will fit onto small propane cans found at Home Depot and Lowes. Propane is much cheaper than ordering green gas and is easier to get. To use the silicon lube you just drop a couple drops onto the propane can before putting the adapter on. As long as you keep your gun lubed you won't know the difference between propane and green gas. I have been using propane for about 3 years now with no problem.