Compressor to Vac Pump ?s

I have just acquired the compressor from a friends Whirlpool refrigerator that they replaced. I wanted to try to turn it into a vacuum pump so that I can do more of my own auto a/c work. Right now I need to pay a mechanic to pull a vacuum on the system for me. I searched the web and there are some articles on doing this. I wonder if someone can help acquaint me with this particular compressor.
It has 4 pipes to it. One is slightly larger than the other three so I'm guessing that's the suction side. All the pipes go into the upper portion of the unit. I don't know why so many pipes? some points of consideration is how the unit was originally cooled. I have read some use oil while others use the a/c refrigerant. As I shake it I cannot hear any oil-in-it sounds. Could I put some PAG oil in it? Anyone done this?

 

OK I'm going to reply to myself after I did a short test of the compressor. Three of the pipes are suction, one discharge. There was some sort of breaker switch incorporated in the wiring that I had to cut out of the system as it only allowed the compressor to run for a few seconds until it tripped. Once I did that it ran until I shut it off. I was only able to get 18 in/hg of vacuum from it no matter which suction pipe I used. I had to plug two while I tested one. Looks like this is not going to work as from my research I need about 30 in/hg and this compressor will not pull that much. Unless anyone has some suggestions I think I will can this little experiment. The unit was free so no big deal.