Fluid leaks are repairs almost every car owner with have to face over the life of a vehicle. Faulty gaskets and seals will be the culprit in the majority of cases when fluid is leaking. With that being said, the reason why a seal or gasket is leaking can be a whole other story. One reason that seals/gaskets fail are due to the fluid they are trying to stop. As the additive package in engine oil breaks down the fluid can no longer keep seals plump and pliable which hardens them and allows fluid to pass. This is one reason why changing your engine oil on time is so critical. Another reason seals/gaskets will leak is due to foreign material contaminating the fluid and acting like little razor blades cutting into the seal. A good example of this is the fluid in the axle housing. When metallic components begin to fail tiny particles of metal from the bearing surface will become trapped in the fluid and over time will damage the axle seal allowing fluid to leak out.