I have a 1999 XJ and took her into the shop because the oil pressure has been low. They used a gauge and found that at both idle and when the engine is hot the pressure is nowhere near where it needs to be. They dropped the pan and there wasn't any gunk in there. They said I might need to drop the engine and put a new one in. It has 82k miles on it so I don't know how since there are so low miles on it. That was last week and today I drove it and heard a nasty squeal especially when I put the clutch in. Attached here is the video of the squealing, the clutch goes in the last 10 seconds
https://photos.app.goo.gl/1e862ebd2xZ3PwHv5

 

If it only squeals when you push in the clutch, I'd suspect it was a worn throw-out bearing. Since it's does it regardless, I'm now not so sure. Does it only do it while moving? If so, it's not the throw-out bearing. Can you tell where it's coming from, approximately?

 

Belt squeal?

 

I would definitely check the belt. The load on the engine changes dramatically when the clutch is pushed in, so it would definitely affect the sound if the belt is slipping.