Wow, thank you very much for the quick reply. As to the lubrication, I really didn't make myself clear. I was under the impression that other compressors rely fully (or at least mostly) on the oil in the refrigerant, whereas the york has the oil in it's own crankcase which never comes into contact with the refrigerant. Or at least as isolated from compressed gas as it could be.

But, in response to your question, I did check the oil in the old compressor after it failed, and it was okay, according to my trusty bent piece of wire.

Do the valves rely on lubrication from the refrigerant oil? I'm not too sure about the oil content of the previous refrigerant, but the inside of the system and compressor (the pistons anyways) seemed nice and oily to me, for whatever that's worth.

I never had an issue with the r134 cooling capacity, but will r12 give me a more trouble free system? I've never really found a straight answer one way or another to that question, opinions seem to be rather mixed.

Thanks again,
Ben Stein