What is an axle shaft seal?
The axle seal is a doughnut shaped piece of flexible material which can be mounted to a metal or hard rubber backing. It prevents a leak at the axle entry point while allowing the axle to rotate as necessary.

How does the axle shaft seal work?
The seal slips over and rides on a smooth portion of the axle shaft. The softer rubber forms to the surface of the axle in order to keep transmission/axle fluid in and dirt out.
What are the symptoms related to a bad axle shaft seal?
A slight axle seal leak may only appear as a damp area around the seal. A more severe leak will result in fluid leaking on the ground. Leaking fluid can also find its way onto the exhaust system, resulting in a burning smell when the exhaust is warm. Excessive fluid loss due to a leak can result in an abnormal noise and/or component failure. On some vehicles an axle seal leak can result in fluid contaminating brake shoes and affect braking operation.
Can I drive with an axle shaft seal problem?
It is generally OK to drive if “seepage” is noted from an axle seal provided the correct fluid level have been verified in the transmission/axle. It would not be advisable to drive with a more severe leak as the fluid loss could result in component damage.
How often do axle shaft seals need to be replaced?
Many vehicles never experience and axle seal leak. If one does occur it would most likely be on a higher mileage vehicle.