I do this to every bushing I install. it helps keep the spring ID from rusting and you dont have to take apart the bushings to grease the OD. these are fluted from factory on the ID but as far as I know you cant buy them fluted on the OD. I use a used cutoff wheel that is of a fairly small diameter, you can get closer to the shoulder that way. also because its worn the edge is radiused not a square edge like a new cut off wheel has. first I cut a slot from the ID flutes to the OD of the bushings of the small dia. ofcourse. then I radially cut a slot til I allmost hit the shoulder. I dont go very deep at all, maybe a 1/16. these bushings are the energy suspension bushings out of some 4 in. TC springs for my blazer. some people say they should be installed dry and the grease is so the steel bushing gets lubed and spins, but I think it should see grease everywhere. just my .02 cents.