It´s not uncommon to have to glue the pushrod seal in, but once sealed it should last 10k miles or more unless the pushrod is damaged or dirty and takes out the seal sooner. I haven´t changed mine yet but it only drips a few drops after every ride then stops till the next ride. It´s a known design flaw (feature?) that goes back to the early 60´s Hondas. Newer small bikes have use a lever on top of the crankcases.