It works and retains your warranty. GM blower oil is for Eaton positive displacement blowers. It's a completely different application than a self-contained gear-driven centrifugal spinning an average of 5-10 times faster than the PD blower.
Do NOT use anything other then ATI procharger oil in it. When i changed mine i looked around online and couldnt find ANYTHING on which oil to use...after a few hours i found an article and it explained all the different reasons and differences in the oil you should use..something about friction modifiers and stuff. Almost reminded me of bike oil for the wet clutch, i just did some digging and cant find it. I had it saved as a fav on my old laptop otherwise i would deffinatly post it. Here is where i order my ati oil from..it even comes with new washers/orings and they ship pretty quick http://www.exoticperformanceplus.com/performance_parts/index.html?item=688