Heads up, R134a

I know of no HVAC techs or companies that recommend any of these "alternative" refrigerants vs. 134a. I read the MSDS sheet on what you are using and it is flammable. It is likely a mixture that contains propane or butane.
134a is a good refrigerant and there is no reason not to use it over these "alternatives" and plenty of reason to use it.
If the "alternatives" were all that good and met all the requirements, don't you think that would be the "official" replacement for R12?
I know of no shop, that has the machines and licensed techs that EVER also use these replacements. A shop that doesn't have the tooling and licensed techs may, but no licensed shop will work on a system that has been contaminated with these "alternatives", they don't want the flammable mixtures in their machines and equipment.
Really, a reclaiming machine isn't that expensive, add to that a device to ID what is in the system and a reclaiming tank, and you are looking at an investment of about $1000-$1500 to properly outfit a shop, then you need someone to study and take the test.
It may not be as much an issue in Canada, but in the litigious US, if a Combine caught fire and burned due to an A/C system, and that fire spread, the shop could be held liable for all the damages.
If you are prepared to use flammables, then propane would be the cheapest way to get an A/C system working again, it is compatible with mineral oil, has lower head pressures and better cooling than even R12.... if you are prepared for the risks.

Mr. Goff I wasn't aiming at you. Sorry!

Mr. Goff I wasn't aiming at you. Sorry!

Not a problem. I just like to relay some real world experience to clear up some of the myths around a product that has been used safely here for years. The name of the product is Duracool, based right here in Canada. It is hydrocarbon based.
http://www.coolearthinc.com/faq.htm

the cheap do-it-yourself kits are RedTek and Duracool, both of which are refined propane/butane mix, and come with the hose & gauge to connect. It says you can use as a direct replacement in a R134a system, but legally you must drain any remaining coolant properly first before recharging. They also sell cans of stuff to stop leaks, and also cans with tracer dye to find leaks. I haven't tried one of the kits myself and am personally on the fence as to their safety (ie: propane) and long term risk to ac system.

the cheap do-it-yourself kits are RedTek and Duracool, both of which are refined propane/butane mix, and come with the hose & gauge to connect. It says you can use as a direct replacement in a R134a system, but legally you must drain any remaining coolant properly first before recharging. They also sell cans of stuff to stop leaks, and also cans with tracer dye to find leaks. I haven't tried one of the kits myself and am personally on the fence as to their safety (ie: propane) and long term risk to ac system.

Neither propane nor butane should cause any damage to the system. They are recognized as refrigerants and have their own R number as class B refrigerants. So as far as that goes it is not a worry. They are generally used with mineral oil lube.
The problem may come if you ever want to use something else, installed by a shop. The reclaim/recycle machines are designed for class A refrigerants and if the shop in question does what they are supposed too, take a sample for ID , and finds Class B stuff in there, refuse to work on it, or require a complete system replacement.
Since A/C systems are (or should be) free of air, there is no risk of combustion inside the system, the problem come if it vents, and in the presents of heat, open flame or spark.
Both gases are very good refrigerants, it is up to you if the risks are worth the benefits.
For me, with the present cost of 134a being low and readily available, it is a no-brainer to go with 134a. With an increase in condenser capacity, it will meet or exceed R12.
What the future holds for 134a remains to be seen, which is what this topic was about.
One thing propane has going for it, It will never be banned as it is used for so many things and is a staple of home heat in rural areas.

My advice: never use a A/C stop leak unless you are DESPERATE. The tubes in some condensors are just so tiny, you could block them off with the stop leak.
Wet hoses, compressor, condensor are all signs of a leak. Always use the green dye on every job so you can see with your eyes, it just makes life easier.
"Filling up" a low A/C system ( without repairs) to get through the hot season is a time-honored event. I just don't think it's a moral thing to do, anymore. Maybe never was.

in all but the tinyest leak, the refrigerant carries the oil with it when it escapes, continual re-filling and the system will be low on oil, then expensive problems happen.
I have read bad reports on stop-leak/ sealers use in AC. I never use them, and buy only can of pure refrigerant, never with stop leak or oil. If oil is needed I add separately
My '92 Marmon had backseat service valve on the compressor, so I could isolate the compressor ,pump the refrigerant out, and check the compressor oil without discharging or re charging the system. None of the new stuff has those valves any more.
I know they aren't popular any more, but the Delco Harrision A-6 is my 1st choice of compressor, big and bulky, but all steel with a capacity of around 40,000 BTU, they are hard to beat. They also have a fair sized oil sump and pressure lube pump built in. Only problem is they have been out of production for 30 years.

Yes, that big GM pump is great! Six cylinders so it's so smooth. Great compressor. Hard to hang one on something newer. Not enough room.

I once saw a Motor coach where the original 4 cyl sutrac compressor was replaced with 4 A-6 mounted in a frame. The Sutrac was over $2000 rebuilt, and 4 Delcos were much cheaper and easyer to source.

Back in the 60's there was the Chry RV-2, the Delco A-6 and then the York/Tecumseh 2 cyl recip. The Delco and Chry were iron and well made, the York was aluminum and cheap, the Tecumseh was a cast iron version of the York. The 2 cyl recip's always shook everything apart, but were the mainstay of aftermarket AC as well as OEM on Ford , AMC and Checker. The A-6 was the best of the bunch but by the mid 80's wouldn't fit were it was needed and the R-4 (a disaster) replaced it. By that time Japan took the A-6 design and made into the small cast aluminum axial compressors common today. The problem with them is the aluminum just doesn't last like the steel and iron in the A-6. All the new stuff is pretty much throw-a-way when something goes wrong.
If rebuilt by a good rebuilder, the A-6 is still a great compressor, rebuilding requires selective fit of the ball and ball seats, if done right it will last a long time, if thrown together with any old parts it will be noisy and fail early.