How new of a Prelude? Honda was using R-134a probably by '93 or '94 .

I'm gonna GUESS that it was probably drained pretty good for shipping. Otherwise the package would have been a mess??

But now I'm gettin in over my head... I know there's some A/C techs around here, I hope somebody can help. There's 3 types of oil, I'm probably confused about which is which:
Mineral oil from older R-12 systems.
PAG oil, compatible with mineral, comes in R-134a conversion kits.
Ester oil, for systems that have ALWAYS had R-134a.
Problem is, I don't know whether PAG & ester oils are compatible with each other.