I'd go for the R134. I've seen the R12 priced as high as $125/can. Check your compressor. If it's sort of short chubby i.e., pancake...replace it with the later model which is roughly the config. of a #10 can, round but much longer than the pancake vervion. If you have the newer one, a bearing replacement would be the way to go. BTW I believe you need a license to buy, sell or install the R12.