AC compressor oil on converted system
 

Read many posts on the subject but still have a question, hopefully the good fols here don't roll their eyes about another AC post :)

I have an 88' that the PO converted to R134 about 4 years ago and still has non- barrier hoses. I just installed a new Denso compressor and need to know what oil to use. Read that you not to use PAG in system used with mineral oil, but the PO mechanic that did the conversion says to use 4 oz PAG.

Should I use Ester oil? Is 4 oz correct? And last question, is it ok to use the oil in pressurized can or add oil before pulling vacuum?

Replace your drier if you have not already.

Ideally, you do not what to mix PAG with mineral or with Ester.
Do some research and determine what the PO used previously
and try to use the same type of oil.

You can pour the oil in the compressor, use an aerosol charge,
use a syringe injector, have an automated machine do it.... what
ever floats your boat.

When you get done, document what kind of oil you used
so the next owner or tech does not wonder about it.
Put a sticker near the compressor with the type of oil
you used. Note it in the owners manual or on a piece
of paper in the glove box.