Return to Blog September 24, 2021

Transmission Fluid and Differential Fluid Failures: Why It Happens and How To Stay Ahead of Problems


While they may not be at the top of your routine maintenance list, transmission fluid and differential fluid are important lubricants that serve a role in any heavy-duty fleet vehicle. The recommended timeline for replacing these fluids varies by manufacturer, application, and environment. For mile after mile, both of these fluids will deteriorate.

Signs Differential Fluid Needs to Be Replaced

There are some telltale signs that differential fluid needs to be replaced, including:

  • The fluid is contaminated with other chemicals or metal particles
  • Grinding noises when turning
  • Presence of water and dirt in the differential fluid
  • Humming while driving due to gears rubbing
  • Increase in vibrations

Depending on your fleet, some vehicles may use a combined transmission and differential fluid. This is most common in front-wheel drive vehicles, while all-wheel drive and four-wheel drive vehicles have separate differential and transmission components.

Signs Transmission Fluid Needs to Be Replaced

A few specific situations are clear indications that it’s time to replace a vehicle’s transmission fluid, such as:

  • Clogged transmission fluid filter, which prevents the normal flow of fluid and results in contaminated fluid
  • Transmission seals have ruptured, resulting in lower transmission fluid levels
  • Slipping gears, sharp or abrupt shifts, or clunking

How Often to Change Transmission Fluid or Differential Fluid? 

Every vehicle manufacturer provides specific instructions for replacing all your vehicle lubricants, including both transmission fluid and differential fluid. Always check with the owner’s manual or work directly with the manufacturer for their recommendation. Many mechanics recommend changing this fluid between 30,000 and 60,000 miles.

Fleet Vehicle Maintenance

Servicing your vehicles regularly is an important part of getting a long life out of your fleet. To make sure issues are caught early on, encourage employees to take weekly notes on their vehicle’s performance, especially if they notice any of the signs of transmission and differential failure noted above.

Only use the very best lubricants in your fleet to ensure more miles and better performance to get the job done.

Avoid downtime from breakdowns and costly repairs. Explore all our Heavy-Duty Transmission & Differential Fluids:

Transmission fluids:

Mobil SHC Gear OH Series

Differential fluids:

Maintain Your Fleet with Tilley Distribution

Having a reliable, quality lubricant supplier is an important part of ensuring your vehicles are running at peak performance for the long road ahead. We offer businesses the best lubricants and dynamic sourcing to make sure we deliver what you need, when you need it. Whether your order is 6,000 gallons or a couple of quarts, you can rely on our commitment to excellent service.

Talk to a Tilley team member today.