Next week we are supposed to be in the 90's already, and I am working on improving the cooling ability of my 240d.

Last year I had a new compressor installed, and the guy I bought it from charged it with 134a. I had a leak last year at the low port fitting, the port itself was leaking.

I identified the leak, and then researched the recharging. I was told that when the 134a is lost, the oil stays in the system - no oil is lost.

So I got some no-oil-added refrigerant and filled to the correct pressures. The system ran ok (didnt cool as good as I need but worked) but whenever I turned off the AC the compressor made a harsh noise - so I thought there must not have enough oil in the system - I added 2 oz of oil and it still made the noise, but was much more quiet after the oil charge.

This year I am going to put the enviro-safe industrial refrigerant in the system. The instructions say to just evacuate the old charge and refill with enviro-safe. Does not mention adding any oil.

So, I guess I am lost - is oil lost when evacuating the system? (I do not mean flushing, just simply when you de-pressure the system).

Thanks for any clarification you guys can provide.