You may want to look into a product that came out last year called Frigc FR-12 by Pennzoil. It is supposed to be compatible with R-12 and does not require any mods to your current AC system other than an adapter nipple to fill in the FR-12. Pennzoil also has a web page: www.frigc.com. I have not tried this stuff in my car so I have no clue on how good/bad it is. Andreas Meyer