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How Often Should I Change Front or Rear Differential Fluid?

When to change differential fluids

 

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.
And in Sioux Falls looking out over 12th St every day, I see a lot of people overloading their light duty pickups!

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 75W-110 ® Synthetic Gear Lube, Severe Gear 75W-90 (Best seller) and Severe Gear 75W-140 are 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

Stay safe out there and visit our Sioux Falls AMSOIL Store at 4610 W. 12th St. (Just west of I29 about 1-block)  605-274-2580

 

Lubricant Viscosity Explained

Lubricant Viscosity Explained

A lubricant’s viscosity and how it changes under different temperatures and operating conditions is one of the most important properties that determines lubricant performance and protection.

Viscosity can be viewed in two ways:

• Kinematic viscosity
• Dynamic (or absolute) viscosity

Kinematic viscosity is defined by the lubricant’s resistance to flow and shear due to gravity. To illustrate, imagine pouring two containers, one filled with water and the other with honey. Each fluid’s Kinematic viscosity governs the rate at which it flows. Since the Kinematic viscosity of water is lower, it flows faster. Kinematic viscosity, measured using ASTM D445 methodology, determines an SAE oil’s high-temperature viscosity grade (the “30” in 5W-30).

Dynamic viscosity, measured by the Cold Crank Simulator (CCS) test (ASTM D5293), is defined as the lubricant’s resistance to flow as indicated by its measured resistance, best thought of as the amount of energy required to move an object, such as a metal rod, through the fluid. It takes less energy to stir water compared to honey because the Dynamic viscosity of water is lower. Dynamic viscosity determines an oil’s low-temperature grade (the “5W” in 5W-30).

What does it mean to motorists? The lubricant’s viscosity at 40ºC and 100ºC is used to calculate its viscosity index (VI) – a measure of how much the viscosity of the fluid changes due to temperature. As we said, viscosity change due to temperatures and operating conditions influences performance. A lubricant that undergoes little viscosity change will generally perform better. A high VI indicates the fluid undergoes little viscosity change due to temperature fluctuations, while a low VI indicates a relatively large viscosity change.

Synthetic fluids generally have much higher viscosity index numbers compared to conventional fluids, meaning they provide improved protection to critical components over a wide range of temperatures. VI is normally reported on the oil’s product data sheet, like this one.

AMSOIL synthetic lubricants boast high VI numbers, meaning they’re more stable than competitive lubricants, so you can count on them to deliver outstanding protection.

New AMSOIL Brake Fluid and Brake & Parts

New AMSOIL Brake Fluid and Brake & Parts

Performance and Reliability

 

New DOT 3 & 4 Synthetic Brake Fluid (BFLV), DOMINATOR® DOT 4 Synthetic Racing Brake Fluid (BFR) and Brake & Parts Cleaner (BPC) help boost the performance, safety and reliability of brake systems.

AMSOIL DOT 3 & 4 Synthetic Brake Fluid, AMSOIL DOMINATOR DOT 4 Synthetic Racing Brake Fluid and AMSOIL Brake & Parts Cleaner will launch April 3. These new products are precisely tailored to the needs of auto enthusiasts and dedicated racers. DOT 3 & 4 Synthetic Brake Fluid meets the highest DOT standards (5.1) and is the perfect choice for high-performance passenger-car, light-truck and powersports applications. DOMINATOR DOT 4 Synthetic Racing Brake Fluid features the ultra-high boiling point required during extreme racing conditions. Brake & Parts Cleaner supplies auto enthusiasts and mechanics with a professional strength, dedicated brake and parts cleaner.

AMSOIL DOT 3 & 4 Synthetic Brake FLuid

  • Maximum ABS and traction-control performance: Low-viscosity, specially designed fluid provides improved cold-weather performance and excellent ABS and traction control responsiveness.
  • Firm brake pedal feel: Maintains low compressibility in severe operating conditions, resulting in consistent brake pedal feel.
  • Helps extend the life of essential components like calipers, wheel cylinders, seals, lines, master cylinders and ABS control valves.

AMSOIL DOMINATOR® DOT 4 Synthetic Brake Fluid

  • Provides vapor lock protection through high boiling points.
  • Resists brake fade common in racing applications for a confident brake feel all the way to the finish line.
  • Nitrogen blanket added to avoid moisture absorption and prevent contamination during manufacturing and storage, ensuring top-quality fluid upon purchase.

Recommendations

AMSOIL DOT 3 & 4 Synthetic Brake Fluid is engineered for use in passenger cars and light trucks. It is a DOT 5.1 product, exceeding the specifications of DOT 3 and DOT 4. Additionally, its 5.1 formula provides excellent protection against water contamination. Rather than offer multiple products, we created one formula that performs best in all three applications.

DOT 3 & 4 Synthetic Brake Fluid is also the primary recommendation for powersports applications. However, if a customer consistently pushes his or her brakes to the limit in racing (or similar applications), DOMINATOR DOT 4 Synthetic Racing Brake Fluid is recommended.

Refer to the owner’s manual regarding the proper change interval for your brake fluid and to determine the correct DOT classification. Change AMSOIL DOT 3 & 4 Synthetic Brake Fluid twice a year for maximum performance. Change AMSOIL DOMINATOR DOT 4 Synthetic Racing Brake Fluid once a year for maximum performance.

AMSOIL Brake & Parts Cleaner

New Brake & Parts Cleaner is a professional-strength product that quickly and effectively removes oil, grease, brake fluid and other contaminants from brake parts and other automotive components. It cleans brake parts with no major disassembly and leaves no residue, helping eliminate brake squeal and chatter.

  • Quickly removes grease and oil
  • Leaves no residue
  • Dries quickly
  • Chlorinated, non-flammable formula
  • VOC-free

Applications

  • Brake Parts
  • Brake Pads
  • Calipers
  • Drums and More

Brake & Parts Cleaner (BPC) vs. Heavy-Duty Degreaser (ADG)

Brake & Parts Cleaner and Heavy-Duty Degreaser are both excellent cleaning and degreasing products. If working with painted, plastic or rubber surfaces, we recommend choosing Heavy-Duty Degreaser.