The main thing with freeze 12 (and some other "alternative" or SNAP refrigerants) is that a lot of them have mixtures or blends. That, in and of itself, is not much of a problem. However, when put into an otherwise leaky system, they tend to fractionate and one part leaks out, leaving (often) the less desirable part to circulate around the A/C system.

With Freeze 12, I believe it is something like 80% 134a, and 20% R142b. The 142 is what carries the mineral oil around an A/C system. Mr. Sargent's experience would be totally logical, because it is likely that the Freeze 12 dumped the 142b part, and kept the R134a part. That TOO is fine, because R134a is a decent refrigerant.

However...

R134a doesn't carry mineral oil. So, sooner or later it hosed up the compressor.

Basically I think from researching Freeze 12 for a while, it would make a fine refrigerant in a non-leaking system. Since R142b leaks out first, the remaining fraction of Freeze 12 doesn't function well thereafter, since basically it is just something you can buy over the counter at any Wal-Mart (R134a). Basically, you'd probably do OK if you either had a non-leaking system, or if you recharged a known, decent system yearly or once every two years. If the R142b leaks out, you're not going to have a functional system for long. However, if it does NOT leak out, the systme will probably work fine for a long time.

There are people on this board who have used Freeze 12 for a long time.

Those are some pro/con thoughts. It pays to know a few details about anything.
--
Chris Herbst, near Chicago.