If you are going to use this for air conditioning do not put anything in there except refrigerant oil. The crank case is not seperate!!!. And by the way never take that plug out with a full charge of freon. If you do bye bye freon. And be careful when you screw that plug back in . If you over tighten it you will crack the case. I know from experance. I can't remember how much oil goes in the sump of the comp but I rember you measure it with a coat hanger.
you could use just bout anything if using as a air compressor but for refrrigerant needs to be refrigerant oil only. ester or mineral. ester is a synthetic that is basically a universal oil and is compatible with mineral and pag which are not at all compatible so it is nice to use as it is really really safe.
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