Review on Injector Including Coupler Refrigerant Charging by Billy Berry

Knowing exactly the amount and type of oil to put in, they add pure R134 which flows better when no oil is mixed in a can. Start with 20 ounces of jet oil and add about 6 ounces of R134. The compressor is now running, stop, add another 2 ounces of oil, empty the 12 ounce can of R134. Finish putting the last 2 ounces of oil in the nozzle, a new 12 ounce can of R134. Empty both, done. Of course, rinse beforehand, if necessary vacuum the lines and weigh the cans. You can still use your gauges to monitor the high side. Ideal for a small or private garage.