* What's the best way to add refrigeration oil to an AC system? Assume that the system has been flushed and holds a good vacuum, and that the compressor, receiver/dryer, and expansion valve were replaced; i.e., the system is empty and clean. The compressor, which doesn't have an oil crankcase (like the old 450s), was installed with about 3 oz of oil in it (any more oil would have run out during installation). Once installed, the compressor was turned, by hand, through a dozen revolutions to displace some of the oil and prevent "slugging" (can't compress liquids). What's the best way to put in another 4 oz of oil?
* Don't own one of the big recovery/recycle units. I've watched them pump oil and a full measured charge into the discharge side with the engine off. But that option isn't open to me (when I get a spare $4K maybe I'll buy one). A vacuum pump, a standard 30lb HFC tank (half full), and a manifold gauge set with an oil infuser attachment is what I have to work with. This is a long post. Thanks for taking the time.