Question for you guys that deal with chillers out there often:

I have an r-22 acme 150 ton chiller that is in our lab, we use it for students to get some time on a chiller. Problem is, the last group that went through filled it so full of oil that it is coming out the access port. The drain plug is positioned in such a way that it is a real pita to drain without making a mess. I have all the pieces needed to make a drain tube down with a shutoff so that we can simply hook a hose up and drain it easily, but i still have a ton of extra oil in the system.

My question is.. can i use a bit of nitrogen (this doesn't have a low pressure disc) to pressurize the compressor while isolated (already recovered refrigerant from the oil) to essentially pump the oil out into a vessel?

thanks in advance for your time, guys.