[gizmofixer]

Our cars are known to have 'porous' hoses and untraceable leaks.
I have used dye and other methods and never locacted my leaks.........
So, i have grown resigned to topping off the system every 2 years or so.

That being said, R-12 is without a doubt the best freon.
Even considering the cost, i suggest refilling with R-12.

R-134 runs higher pressures and is not as effective cooling.
You can convert to R-134 without changing any oil or the dryer.
Your tech just needs to be aware that the system will require more qty R-134 than the conversion charts show and the pressures will run correspondingly higher than a R-12 system.

WHATEVER YOU DO, DO NOT USE FREEZE 12, AUTOFROST OR ANY OF THE OTHER SO-CALLED FREON REPLACEMENTS.

These products contain propane, methane, esthers, alcohol, and other contaminants which are ineffective, dangerous, corrosive, and will eventually kill the environment, your system and possibly your tech.