Rod, supercharger oil is made of animal fats. It cooks itself daily. That'* why it stinks so bad (smells good to a dog though, trust me.....Bo likes it used, but prefers new).
Dealers go by what GM tells them. There stance on supercharger oil and repairs have changed due to 'company directives' several times over the last few years. It used to be they would only change the entire supercharger for a nosedrive coupler rattle. Now they stock nosedrives and are allowed to replace them seperately. In which case, you'd THINK they'd have to have supercharger oil in stock.