Probably a dumb question but did you check for dye in the condenser? if everything else isn't showing dye that's the only other place I can think of that would be capable of such a huge leak. ie. a hole in the condenser

All I can think of is penetrating oil spray. spray it on the threads that are already visible screw it back in let it sit for an hour or two to let the oil do its thing and then try again with the autozone tool / pliers. doing anything else risks stripping or damaging the threads.

I have a 2003 Nissan frontier XE 3.3L V6. I recently noticed a lot of fresh oil residue above and below the ac compressor. I have noticed that if I start the truck with the a.c. on and fan at full power I can hear a loud squeal that lasts anywhere from 2 to 10 seconds. If I turn the a/c off the sque...