Okay, I recently purchased a 2001 Pontiac Grand Prix GTP (Quite the step up for me from the Focus). This is the first car I have ever owned that has forced induction (supercharged). I know the snout on the Eaton M90 supercharger has oil in it and beside it being the most haneously foul smelling stuff ever, I know nothing about it. I know there is debate as to whether it ever needs changed or not, the manual doesnt specifically call for it but help me out with my curiousity. Know one seems to have any info as to what weight oil this is or its make up. I searched for a UOA and VOA but came up empty other than one post with not a whole lot of new info. So does anyone know. I changed the coupler in the snout this weekend and ended up re-using the oil because none of the GM dealerships here in town had any of the Supercharger oil but I'd like to change it out just for my own peace of mind and becuase Im just finiky that way. I would surely appreciate any info. I suspected it would be a gear oil, but someone on one of the GP boards said a gear oil was too thick and after sucking that stuff out I would say it probably would be. I havent a clue though to what could stand up to that kind of RPM (I think it turns around 11k RPM if I have my fact straight) and the heat. I would like to use an Amsoil product, but I contacted them and they dont have any replacement for it, so for now Im just out to satisfy my curiousity as to what the make up of this stuff is. Once I get some replacement oil I think I'll get some extra and send it off for analysis just for grins and giggles.