If the car is setup for R134a, the fittings are unique. It must be '94 (or '93) that R134a was mandated for use in US cars. My bad.
The point behind the oil is that it is dissolved in the R134a (and not all oils will dissolve). Chemically, the oil is 100% miscible in R134a. That means where the liquid R134a flows, so does oil. Even R134a gas has oil vapor. Hence, if there is a R134a leak spot then oil will leak there also. Good luck!