How Often Should I Change Front or Rear Differential Fluid?

Chevrolet Towing Camper

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

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Comments

  1. Thanks sir for posting such an informative blog.It is so helpful for the customers who wanted to know about changing of fluid in their vehicle.However the answer is universal to each vehicle as fluid change depends on your vehicle,driving conditions and quality of different fluid.The thing is that if you are driving your vehicle in high temperature region then there is no need to change the fluid often.But if you drive the car in that region where the temperature varies time to time then you need to change the fluid.The only way to know the exact time interval for fluid change is to check your owner’s manual or visit the dealership.

  2. This blog post is absolutely on point.

    2013 Ford Expedition RWD with 5.4L and 9.75 Rear Gear.

    In the owner’s manual, Ford recommends changing transmission and differential fluid at 150,000 miles. I regularly tow a 9.500 lb travel trailer and a 3,000 lb utility trailer. At 60,500 miles I just changed my transmission fluid to Amsoil ATL (and the transmission filter) and the rear axle with Amsoil SVO (2.75 quart capacity). BOTH fluids drained out were “brown” in color and showed signs of thermal degradation.

    I am looking forward to my first full tank of gas and seeing the change in my fuel economy. Since I began using Amsoil products in 1989 I’ve seen an increase in fuel economy and a reduction in normal operating temperature in every vehicle I’ve owned when I have installed Amsoil products throughout the drivetrain (motor oil, transmission and differential fluid).

    I’m grateful to Amsoil for the high quality products they provided to me for almost three decades.

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