I have been working with refrigerants since 1970 when a hutterite came over to put a homebuilt system on our 503 IH combine and was hooked ever since . On our older tractors and trucks that have leaky hoses I use red teck which works great as it seems to get colder than the old r-12 and no oil change . With the newer units I will charge with 134 and replace shaft seals when available ( seems like the availability of seals is getting harder to come by as the world is going to replace rather than fix ) other than getting a rebuilt compressor . I use four seasons as my part source ( since they bought out everco which was a better supplier ) . In my province ( Manitoba) you can not work on any refrigerant unit without being trained in cfc recovery and handling and you get a Manitoba ozone protection industry association ( MOPIA ) card - can't even get a dust cap for the charging ports . I have a 75 ford f-100 and the AC is charged wit R12 and still working great . All in all I think that some regulation in the refrigerant industry is a good thing as there are too many jokers that are dumping or just adding cans of refrigerant to be lost in the atmosphere . Don't know if the ozone is really that worth worrying about but I hear that the holes are closing up so something good has happened from all this . With the new refrigerants coming out I am not going to play with these as some are really expensive and hard to get - even heard of them going to carbon dioxide systems very high pressure .