What oil for A/C

ok, i've been doing all this research on converting my A/C to a comp. and i put it all together, but i was reading here in my Haynes book and it say the make sure you use oil compatible with R-134a refrigerant systems? i'm wondering if i could just use normal air tool oil or do i need somethin special. i'm not about to spend this time hooking it all up just to fry the bitch cause of the wrong oil.....someone taht has done this please help me out. thanks