The rubber used in the seals now is not real rubber, seems like once grease hits them they fail pretty fast. If you ever go into a Harbor Freight store, you can smell the tires across the store, this is the same stuff. I have a couple old bikes I restored, the tires go flat all the time, the air just seeps out through the tubes, no holes, just everywhere. I'm not sure it should be called rubber anymore. I had a PCV valve grommet swell up twice its original size.
