Skip to main content

Texas Heat Proof AMSOIL Gives Transmissions a Break

AMSOIL Synthetic Transmission Fluid Tames Texas Heat

Not even a “spot” of sludge in the pan or on the filter despite extreme heat & heavy towing.

BTB Services owner Bryan Bayles and employee Oscar DeLeon stand by the company’s 2015 Chevy 2500, which is still running strong thanks to good maintenance and AMSOIL products.

by John Baker | December 2022

Customer Bryan Bayles, out of Katy, Texas, saw a need while working as a groundwater sampler and turned it into a successful business. “We used to go to these sites that were really hard to get to because they weren’t being maintained,” he said.

Neglect and disuse often turned groundwater sampling sites into jungles of overgrown weeds and brush, sometimes teeming with rats. Today, Bayles’ company, BTB Services, does what’s called “post-closure care.” His crew maintains groundwater-testing sites around refineries and other sites so they remain accessible.

“One site was 25 acres and in the middle of a town,” said Bayles. “People started complaining about rats running out of it.”

Much of the work involves using tractors, zero-turn mowers and handheld equipment to cut large areas of grass and brush.

“We take tractors out and weed eaters to get the paths clear so we can get out there,” Bayles said.

BTB Services operates three large mowing tractors, two zero-turn mowers, a skid steer and a brush mower. Being a stickler for maintenance, Bayles uses AMSOIL products in his vehicles and equipment.

Vehicles Must Face Brutal Texas Heat

His vehicles include a small fleet of half-ton and larger pickups that transport equipment to sites using gooseneck trailers. Working in the scorching Texas heat means BTB Services’ trucks are exposed to temperatures that frequently exceed 100°F (38°C) for a good part of the season. Combined with towing up to 30,000 pounds (13,607 kg), the company’s vehicles are the epitome of “severe-service” work trucks.

One such truck is a 2015 Chevrolet 2500 that Bayles bought in 2015. Bayles does as much maintenance as he can himself, including changing transmission fluid and filters. When the truck had about 50,000 miles (80,000 km) on it, Bayles switched the transmission to AMSOIL Signature Series Synthetic Fuel-Efficient Automatic Transmission Fluid.


Internal Transmission Filter Never Changed

Given the severe conditions, Bayles changes transmission fluid every 30,000 miles (48,000 km).

“I know that’s extreme, but we’re pulling about 30,000 pounds of weight behind the trucks,” he said. The maintenance strategy plus AMSOIL product performance have helped the truck eclipse 300,000 miles (483,000 km) with no issues.

Bayles changes the external, spin-on transmission filter on the Chevy 2500 every 60,000 miles (96,500 km).

However, since the transmission includes a drain plug and doesn’t require dropping the pan, he didn’t realize the transmission also has an internal filter, meaning it was never changed.

“I felt horrible that I had 300,000 miles on the truck and I never had the pan off,” said Bayles.

“Spotless! I can’t believe it.”

So, after 257,000 miles (413,600 km) using AMSOIL synthetic transmission fluid, Bayles dropped the pan to change the internal filter, unsure what he would find. The cleanliness of the pan and fluid amazed him; there wasn’t even a hint of sludge or deposits. He texted his AMSOIL Dealer, Erroll Ivery, an image of the clean pan and pristine fluid with the words, “Spotless! I can’t believe it.”

Transmission fluid still clean after Texas Heat and abuse of maximum towing.

The transmission pan and filter contained no sludge or deposits; the fluid still appeared in like-new condition.

Bayles said there wasn’t even a film of deposits or sludge on the transmission filter.

The Chevy 2500 has about 315,000 miles (507,000 km) on it now and still runs great. “Right now, I have it pulling a 32 foot trailer,” said Bayles. Including the payload, that adds up to about 22,500 pounds (10,200 kg). “I gave it a little bit of a break,” he said.

AMSOIL Synthetic Motor Oil Also Delivers Premium Protection

BTB Services has four trucks, two diesel and two gas, all of which use AMSOIL products in the engine, transmission, differentials and cooling systems. All the company’s diesel tractors use AMSOIL products, too. “We started using AMSOIL in our zero-turn this year,” he said.

Bayles performed oil analysis on the engine oil in his trucks, and the results showed the oil in his gas trucks still had 20% oil life following 20,000 severe-service miles (32,000 km), while the diesel oil still had 50% oil life after 10,000 miles (16,000 km).

AMSOIL products help Brian Bayles keep his trucks and equipment up and running, making money, which is vital for any business. “It definitely has helped keep the equipment well-maintained. I have never had any problems with the vehicles I maintain,” he said.

Bayles isn’t shy about telling others about his AMSOIL success story. “It’s a product I definitely highly recommend,” he said. “I believe in putting the best in all my equipment.”


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.


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.


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


  • 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.