How Often Should I Change Front or Rear Differential Fluid?

It depends on your vehicle, driving conditions and differential fluid quality.

That’s a pretty vague answer, but it’s true.

If you drive your truck primarily on the highway in temperate conditions and rarely tow or haul, you likely don’t need to change front or rear differential fluid very often. But, if you tow a work trailer or haul supplies frequently and the temperature fluctuates as wildly as your health insurance premium, then you need to change the fluid more often. The only way to know the exact mileage interval is to check your owner’s manual or visit the dealership.

Bigger, faster, stronger

Why the varying fluid change intervals? Because severe operating conditions break down differential fluid more quickly and place greater stress on the gears and bearings, inviting wear.

The truck manufacturer’s ongoing arms race for the highest towing capacity has resulted in trucks that place far more stress on differentials than their predecessors. Meanwhile, differential fluid capacities have largely decreased or remained the same.

For example, compare a 1996 Ford F-250 Crew Cab to the 2017 version. Back in 1996, maximum towing capacity was 10,500 lbs. using a rear differential that held 3.75 quarts of gear lube. The 2017 model offers a 15,000-lb. towing capacity using a rear differential that holds 3.5 quarts of fluid.

Greater towing capacity, less gear lube

What does that mean for your truck? It means less fluid is responsible for guarding against increased heat and stress. In this environment, inferior lubricants can shear and permanently lose viscosity. Once sheared, the fluid film weakens, ruptures and allows metal-to-metal contact, eventually causing gear and bearing failure.

Increased temperatures are also a challenge. As temperatures climb, gear lubricants tend to lose viscosity, while extreme loads and pressures can break the lubricant film, causing increased metal-to-metal contact and heat. The increased friction and heat, in turn, cause the lubricant to lose further viscosity, which further increases friction and heat. Friction and heat continue to spiral upward, creating a vicious cycle known as thermal runaway that eventually leads to greatly increased wear and irreparable equipment damage.

That’s why you need to change differential fluid more often in severe operating conditions.

In our example above, Ford recommends changing differential fluid every 150,000 miles in normal service. But they drop the change interval significantly – to every 30,000 miles if using non-synthetic fluid – when towing frequently at wide-open throttle and driving at temps above 70ºF. Those restrictions apply to just about anyone who’s pulled a camper/boat/trailer anywhere in North America during most of the year.

Bottom line…

Use a high-quality synthetic gear lube to maximize your truck’s ability to tow and haul.

AMSOIL Severe Gear® Synthetic Gear Lube is specifically designed for severe service. It maintains viscosity better than other conventional and synthetic gear lubes despite rigorous use and it contains advanced anti-wear additives for further protection. It also costs less than most OEM-branded gear lubes.

FIND AMSOIL SYNTHETIC GEAR LUBE FOR MY TRUCK

Oil Analysis Kits Available from Oil Analyzers Inc. Ed Newman|May 10, 2022 2:38 PM   In order to provide a cost-effective oil analysis option when a full fluid analysis is not required, Oil Analyzers Inc. has launched a new Oil Analyzers Value Kit that focuses on the most critical used-oil analysis tests. It provides less […]

Racer Secrets: Tips and Tricks to Help on Race Day Lindsay Premo|Oct 16, 2020 8:00 AM Happy October, race fans! There are a lot of things we know are necessary in racing. A helmet, driver’s suit, gloves, appropriate footwear and (obviously) something to race on/in are all essential to striving toward that checkered flag. But, […]

First Time Heading to Sturgis? We’ve Got Some Tips. Jamie Jarvi|Aug 03, 2016 9:26 AM The Sturgis Motorcycle Rally is a true bucket-list destination for any motorcycle enthusiast. Each year thousands upon thousands of riders descend on Sturgis, S.D., and turn this small, sleepy town into a motorcycle mecca. Some travel the road to Sturgis […]

AMSOIL synthetic motor oil helps you breathe easier Oxygen is great in your lungs, but it’s not so great in your motor oil. Matt Erickson | VP, PRODUCT DEVELOPMENT Oxygen comprises about 20% of our atmosphere. It’s the third most common element in the universe. Without it we’d all be doomed. Yet, oxygen can cause […]

How to Maximize Marine Engine Performance and Reliability John Baker|May 02, 2022 10:36 AM   Fishing opener is right around the corner for us Northlanders. It’s essentially a regional holiday, rivaled only by the opener of gun deer season in the fall. Although some boaters and anglers don’t realize it, using a dedicated marine motor […]

Zeroturn Spindle

Best Practices for Your Zero-Turn Mower First, we’ll start with a question. How did we survive before Zero-Turn mowers? What did they do in the 50’s? Did they not cut the grass? Chris Sharon|Sep 07, 2022 8:00 AM Here at AMSOIL, we’re always investigating ways we can help you get the most out of your […]