I put the RED TEK 12a in my car at the start of summer. Have a small leak that needs about a can a year to cycle the compressor properly. I ran out of R12 4 + years ago & haven't had AC the last 4 summers. Ended up putting in 3 cans of RED TEK & AC has been working fine all summer. Be aware it is more flammable then R12 but so is the gas in our fuel rails.