I'm using 100% hardware store propane as my refrigerant. My 89 300SE had already been converted to R134a & Pag oil when I bought it last March, and it cooled the car well enough for a normal, mild summer in northern Illinois. However, I took a trip to St. Louis during one of their famous heat waves last July, and sweltered the whole time.

When I got back I did a lot of research on the subject of alternate refrigerants, including on this forum and decided to give propane a try. It works very well. Far better than R134a in my old Benz system. I don't have anything against R12, except for its cost. As others have pointed out there's still plenty of it around.

First I made up an adapter that would allow me to connect a standard Benz-o-matic 14oz. (the exact amount needed) propane tank to the R134a low side fitting. I had my local indy recover the R134a, then I vacuumed the system down and recharged with the 14oz. of propane as a liquid. Total cost of refrigerant, less that $3.00 from my local Ace hardware.

Works great, even in St. Louis heat waves! And, you gotta love the price.

Btw: The only physical change I made to the car was to install a new dryer. It looked really old, maybe the original, so it was time.

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2000 Mercedes S500
1990 Mercedes 560SEL
1970 Triumph Spitfire