when cars started having airconditioning, the only refrigerant was R12 (dichlorodifluoromethane) or CFC12 or as commonly called freon was designed to use de-waxed mineral oil. then the mineral oil was replaced with POE (polyol ester), a synthetic oil that does not contain wax and is not petroleum based.
with the bad effects of R12, the depletion of the ozone layer, the U.S. congress required the car manufacturing industry to switch and discontinue installing freon in cars made from 1995, hence, the replacement to R134a (tetrafluoroethane) which does not contain chlorine, the harmful chemical that tore the ozone layer.
with this switch to a newer refrigerant, cars still on the road that once used freon, were retrofitted and could use POE or could use PAG (poly alkylene glycol)

if the car was produced 1995 or later, the refrigerant is R134a and the recommended oil is PAG. the mineral oil or capella oil produced and sold by caltex is not compatible with R134a and can damage the compressor prematurely