Never add more than an ounce to an older system, and thats only if you know for sure it has not already been done. If there is any doubt at all, the only safe thing to do is drain the system completely which includes removing the compressor, and then add 4. ounces to an empty system.
This is an extreme case of more is worse. Oil does not compress the way gas does, and the strain on the system of trying to compress ANY excess oil will be disastrous. The rest of MY OPINION is that adding addl oil, even per the TSB, is dangerous to an older system, especially one already in distress.
The bulletin was meant only to prevent damage, never to fix it. Excess noise is a result of excess wear. (warning- Pontification ahead) Period. The wear may be in a bearing, or the compressor itself which is most likely. If you wait too long, you will spend alot more money to fix it, as Drew pointed out.
It aint the black death, its the black cost a fortune.
PM me if you would like the ND compressor number to buy it elsewhere for less than Mother sells it for. About 400. less.
Good Luck,
MB