I tried to install an SKF 11124 oil seal to a 6204 bearing, but it will not work.
It was a nice tight fit pressing the steel frame of the seal into the bearing outer race groove that holds the original seal. It was so tight it caused the frame to deform a bit on the adjacent side. This seal has two sealing surfaces, one for sealing oil, and another dust seal. The oil sealing part is on the inner race, and the dust seal is overhanging. The problem is the oil seal is too tight on the inner race. It creates a lot of drag and the inner race gets hot when run at a high speed. The seal eventually began to burn. But, a better seal may be possible. This exercise is to see if a better seal if possible on a bearing this small.