Originally Posted by SenorFunkyPants
Not at all to be recommended. The diff clutch pack is designed to operate with high levels of friction between the plates, putting additives into the diff oil may degrade the friction level such that the Limited Slip part of the Diff would no longer function correctly although it would at least be quiet.
However, he was correct. That was the solution provided by GM for the C6. They recommended a GM-branded additive only (name escapes me at the moment). Not all diff. additives are created equal, and I think you are also correct that some additives could compromise the proper function of the LSD.
FWIW, GM also stated that it was OK to take no action, but like here, many complained about it. They decided to address it with the additive if a customer wanted it attended to.