Change over to the Propan / Butan mixture known as Envirosafe ( and other mixtures of the same ) . I am using it in my 87 GTI (sold), our 81 XJ6, our sons SVX and in my 93 V8. You shold change over to R124 fittings and add a sticker to the car. One of the advantages is, that you don't even have to evacuate the system. ( I do evacuate mainly to check for leaks.) The system pressure is lower and the mixture cools more than R12. FYI , if I remember right Albert Einstein used this mixture as well.
