I got around to reading more about this, and it turns out duracool is illegal to use in the US.
Unacceptable Substitute Refrigerants | Alternatives / SNAP | US EPA
HOWEVER:
There is a very similar hydrocarbon based refrigerant,
[HCR-188c] that has been developed by a Hawaiian man and has
very recently been approved by the EPA.
Can't wait to get my [strike]hands[/strike] car on some of this stuff.