Most of the FC's are highly toxic when exposed to fire. R-1234yf is not only (slightly) flammable but also releases hydrogen fluoride and carbonyl fluoride whe

Most of the FC's are highly toxic when exposed to fire. R-1234yf is not only (slightly) flammable but also releases hydrogen fluoride and carbonyl fluoride when exposed to fire, but this is what is in almost all new cars. I've run a propane/butane mix in an R12 car before and the fact that it was flammable didn't bother me a bit. The 14 gallons of gas would worry me more than 12oz of propane going up.