Review on Aupoko Injector Refrigerant R 134A Coupler by Phillip Ellis

Just received R12/R134A AC oil and dye injector. I read reviews of similar products and decided on this one. The back or bottom (the knurled part without the hose attached) is not removable. Any attempt will destroy it or render it unusable. However, you can easily unscrew the knurled part with the hose connected! I need to add 4-6 ounces of oil to my truck's A/C system to replace the metering valve and reservoir/dryer. There is a sticker on the inner tube with a maximum capacity of 2 oz. or 60ml. Unfortunately I have to do this multiple times to get 4-6 oz. Once the top is unscrewed, be sure to unscrew (unscrew) the bottom to reveal the required amount of oil plus about 1/8 oz. (3.75 ml) to balance the exhaust air. Add your favorite HVAC oil flavor to the carving. Unscrew the top, hold the injector upright while routing the hose, and bleed the R12 schrader valve at the end of the hose. Rotate the body of the hose about 1/2-1 turn (to expel the air) and depress the R12 Schrader valve. Repeat this until only oil comes out of the Schrader valve, which tells you there is no more air in the oil chamber or hose. If you work with R134A, please install the included R12-R134A adapter. Follow the manufacturer's instructions for maintaining the air conditioning oil! Some reviews complained about the brass ring in the R134a coupler. Push to install sleeve and pull blue collar to unlock and remove. Some couplings have this brass element, some don't. It depends on the manufacturers and their air conditioners. The supplied adapter fits "most" R134A systems. You may need another R12 for your vehicle's AC system, low side adapter. This oil and dye injector has worked on: 95 Chevy k1500, 97 Chevy Corvette, 06 VW Jetta TDI and 2011 Audi Q7.