I had a shop replace replace pretty much everything in the A/C system except the evaporator and condenser in 2008. It's a '95 so it uses R134A. It got weaker the past few years and recently it started short cycling because the pressure was too low. I bought an 18 oz. recharge kit (no dye, no oil) and it surprised me when it took all 18 oz. to get the pressure back up to 40 p.s.i. at 75 degrees (with the compressor running). My Hayne's manual says it uses 28 oz., so it lost 64% of its refrigerant. Did it lose 64% of its oil? How much of what oil do I need to add to protect the compressor? The receipt says they used $28 worth of FrigiQuiet in 2008 (not the amount). I can get 3 oz. of PAG 100 at Walmart for about $7. Yes, I know it has a leak. I will know how bad the leak is by how long it takes to start short cycling again. I did try searching this forum, but I did not find answers and eventually I was asked to donate to the Red Cross or it wouldn't let me search anymore.