Bryan,When you open the gun all the way and the piston is pulled out of the cylinder as far as it will go. place a drop or two where the piston and the edge of the cylinder meet, and when you cock it the oil will travel to the o ring in the cylinder. I have several of these and use non detergent oil (Pelgunoil), Macs secret sauce, Super lube oil and they all work equally wellI believe in these guns.