Well the a/c compressor is locking up on my 300D. Will adding oil help or once it gets this far does it just need to be replaced? Thankfully its getting cooler so the a/c isn't a must.

If it's seizing it's probably too far gone.

I'd also make sure it's disengaged until you can repair it. I think there were posts about a thrown belt trashing an oil line. Generally bad things happening.

Check the high side pressure, if it is OK = remove the A/C belt before the compressor locks..
Catastrophic failure is never good.

I removed the fuse for the climate control since I was on the road when it started. I already have a weeping oil line and am planning on changing them this weekend so I should be okay there.

The system has been cooling well so I am assuming the freon (R134A) level is fine.... we all know what happens when you assume something

I guess I can add an R4 compressor to my list of needed parts.... even with all of the parts needed to bring this car back to spec I am still going to be in well under $2000.