Other information:
Replacement And Air Bleeding
Never remove the radiator cap when the engine is hot. Serious scalding
could be caused by hot fluid under high pressure escaping from the radiator.
...
Oil Specification
1.
The HFC-134a or HFO-1234yf system requires synthetic (PAG) compressor
oil whereas the R-12 system requires mineral compressor oil. The two
oils must never be mixed.
2.
Compressor (PAG) oil varies according ...