auto 1985 mercedes 380 se.?

There is a plug on the side where you are to put the oil in but putting it in to the back through one of the connecting ports is fine . just be sure to rotate the compressor by hand after the lines are connected and before the belt is in place . this is to clear the compressor of excessive oil which can be damaged on initial engagement if not done so...

Types of oil...if you are converting it from R-12 to R134 you need to use PAG oil if not Ester oil or any oil designed for automotive A/C systems will work ...both of which are available from NAPA stores.....

Regardless of what others may tell you ,the early Benz W126 chassis such as the 85 use a G.M. compressor and no special A/C oil is required unless you are converting it

Hopefully you are also changing the receiver dryer...a must when replacing a compressor and if the old one has seized an expansion valve and system flush is required for a repair job that will perform properly and last