You should rebuild it when pumping takes a really long time or there are other issues. How long it takes depends on usage and how you pump. It will last a lot longer of you take a few second for each up and down cycle instead of going at it like a rabbit Go for 50 strokes and then let it cool down for 10 minutes. Some people also recommend turning the bleed screw to get rid of any moisture. Lubing would again depend on how much you use it but all you need to do is apply a very thin film of silicone grease to the pump shaft. A little dab will do ya so they say. No need to disassemble the pump.