The differential is one of the most commonly overlooked service in personal transportation. It is important that differential service gets the attention it deserves, especially under severe conditions such as heavy loads, high temperatures, and stop and go driving. It is often recommended to change the differential gear oil every 15,000 to 30,000 miles. Going a long period of time without servicing your vehicle differential can lead to gear oil breakdown, cause poor differential performance and noise, allow excessive wear and corrosion of gears and internally lubricated parts, and contribute to premature differential failure and replacement.