I use a halide torch to look for leaks. Not a big fan of adding anything other than oil or refrigerant.
Ah a man who is after my heart. Good old Halide torch.
True story. Years ago my dad was installing a showcase on Madison Ave. in NYC.
Dupont salesman had just convinced him how great Methyl Chloride was so his helper grabbed the Halide Torch to look for leaks. Ironically the kid happen to turn his head when he lit it and BOOM
The kid my father,salesman and showcase wound up on the other side of the street.