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

President and Force behind AMSOIL's growth

From The President AMSOIL INC Fall 2020 Message to Preferred Customers This issue of the Fall 2020 Preferred Customer AMSOIL Magazine has a nice feature on the history of the Ford* Mustang.* I’ve always been a Pontiac* guy, but there’s no denying the Mustang’s place in American muscle-car history. It has been a hot summer […]

Deposits minimized on turbocharges using AMSOIL

Turbocharger vs Supercharger: What’s the Difference? John Baker|Oct 16, 2020 10:06 AM An engine is nothing more than an air pump. The more air it ingests, the more fuel it can burn. And more fuel equals more power. Sometimes an engine just needs a little boost Engineers have a few methods at their disposal for increasing […]

enjoying boat before winter storage

How to Winterize Your Boat and Motor Frank Cannon | September 2020   Recently, I’ve become the owner of my first boat, a used pontoon with a two-stroke outboard motor. I’ve been dreaming of fishing with my buddies out on the St. Louis River on a calm, crisp summer morning. Unfortunately, living in northern Wisconsin […]

8 Ways to Prepare Your Snowmobile for Riding Season Jamie Jarvi|Nov 18, 2016 10:15 AM Old man winter is making his official entrance this weekend with the season’s first snow storm lumbering across the Midwest. Winter enthusiasts have been anxiously awaiting the chance to take their first snowmobile rides of the season, and the time has […]