We're about to find out.

When I had my w123, I bought a brand new Hodyon/Hancock Industries compressor. used 134a. I flushed the entire system, and 134a has higher head pressures than r12, so the the compressor would stop spinning with the clutch engaged. Well, it burned the front bearing out.

So I replaced the bearing, and flushed and replaced drier again, and then switched to Duracool. Wow, it worked very well, and had less pressure than the 134a. Never has a clutch burn or compressor failure after that.

Yes, the hydrocarbon blends (usually Propane/Isobutane) like Duracool, Enviro-Safe will give you icicles at the vents at speed but don't cool as well at idle as r12 though better than R134 which keeps you warm at all speeds in addition to destroying your compressor and worsening your fuel mileage.

Did you notice the jolt your engine got when you turned on the ac when you had it running on R134 compared to the almost imperceptible difference when turning it on now with the Duracool?

The instructions I have here read, "Use a refrigerant identifier to verify that the refrigerant in the system is not contaminated with a blend refrigerant or has a high concentration of air."

I plan on having it flushed and charged by a local shop I trust. I'll ask them about it.

Yes, big difference even while driving. Sadly, I do not have my w123. But I do have a w124 that I will be switching to Duracool.