Change Gear Lube After Break-In Period for Long Differential Life

Unbeknownst to many motorists, most differntial wear occurs during the break-in period. AMSOIL encourages motorists to change their gear lube following the break-in period in order to reduce wear and extend differential life.

Motorists know when they're supposed to change their motor oil. They have oil life monitors, oil change centers and commercials all telling them when it's time for an oil change. Differential oil changes, on the other hand, often get overlooked. Many people don't even think of the differential when performing routine maintenance on their vehicles and don't realize four-wheen drive trucks have two differentials and a transfer case that all require service. In fact, according to one quick lube company, only one to two percent of their customers purchase a differential gear lube change.

Most differential wear occurs during the break-in period. Beacause differentials are not equipped with filters, break-in metals are suspended in the oil, causing increased wear as the particles mesh between the gears. Hauling heavy loads and towing heavy trailers cause additional stress to the differential during the break-in period and can cause premature differential damage or failure. Changing the gear lube after the break-in period (about 3,000 miles) is a low-cost maintenance investment that provides a significant payoff, including greatly reduced wear, extended differential gear and bearing life and protection for expensive vehicle investments. Auto manufacturers recognize the importance of draining abrasive break-in materials. Some manufacturers recommend an initial drain interval of between 500 and 3,000 miles.

Differential internal components consist of six gears (one pinion, one ring, two side and two spider gears), six bearings (two pinion, two carrier and two axle) and sometimes include a clutch setup for limited slip performance. All of these parts require high quality, clean gear oil in order to perform at an optimal level.

Most pickup trucks, SUVs and vans operate in severe service conditions, including towing, hauling, steep hill driving, commercial use, plowing, racing, off-road use, rapid acceleration, frequent stop-and-go operation and high ambient temperatures. These severe service operating conditions subject the differential to extreme pressures and operating temperatures.

New vehicles such as turbo diesel trucks and vehicles with V-10 engines boast more horsepower and torque than their predecessors, but differential designs have remained virtually unchanged. Differentials today are subjected to severe duty service and encounter more stress and heat than was seen only a few years ago. Modern gear oils are faced with the challenge of providing adequate wear protection during severe service operating conditions, while also providing maximum fuel efficiency.

In fact, according to a 2005 SAE paper entitled Breaking the Viscosity Paradigm: Formulating Approaches for Optimizing Efficiency and Vehicle Life, "Concurrent with the strong drive toward better fuel economy, consumers have been demanding increased performance, which has required axle lubricants with enhanced durability protection and lowering operating temperatures. There has been a 34% increase in engine horsepower over the last decade, while axle gear sizes have remained constant, sump capacities have been lowered, and drain intervals extended. In the light truck segment there has been a 93% horsepower increase since 1981."

Further evidence of stress and increased temperatures during the differential break-in period is documented in a 2005 SAE paper entitled The Effect of Heavy Loads on Light Duty Vehicle Axle Operating Temperature. A light duty GM truck towing 14,000 pounds was driven from Orange County, California to the Nevada state line. The test was conducted with both a new axle and a broken-in axle. Over level ground towing, oil temperature was measured at 230 degrees F in the new axle and 203 degrees F in the broken-in axle. Oil temperature over the most grueling portion of the trip, during which a maximum 6% grade was encountered , revealed the new axle was operating at 350 degrees F and the broken-in axle was operating at 300 degrees F. Laboratory dynamometer test results simulating a truck hauling a trailer provided similar results, with level ground towing temperatures recorded at 266 degrees F with the new axle and 194 degrees F with the broken-in axle and towing temperatures (at a 3.5% grade) recorded at 370 degrees F with a new axle and 295 degrees F with the broken-in axle.

AMSOIL SEVERE GEAR 75W-90 and AMSOIL SEVERE GEAR 75W-140 Synthetic Gear Lubes are formulated for severe service applications, protecting differential gears for extended drain intervals of up to 50,000 miles in severe service and 100,000 miles in normal service, or longer where specified by the vehicle manufacturer. Formulated with shear stable synthetic base stocks and an extra treatment of additives, SEVERE GEAR Gear Lubes provide unsurpassed wear protection and friction reduction, while their excellent thermal stability prevents thermal runaway, a phenomenon caused by a lubricant's inability to control friction and increased heat under high stress conditions.

AMSOIL SEVERE GEAR Synthetic Gear Lubes are recommended for turbo diesel pick-ups, SUVs, vans, delivery/utility vehicles, light, medium and heavy-duty trucks, buses, heavy equipment, 4x4s, tow trucks, race cars, tractors and motor homes.

AMSOIL Synthetic Gear Lubes save motorists money through extended drain intervals, and they also cost less per quart compared to many competing OEM gear lubes.

A test on four seperate vehicles further demonstrated the importance of changing the factory-fill gear lube within the first few thousand miles. Oil analysis results revealed most of the wear on vehicle one occurred within the first 6,869 miles. Despite higher mileages, vehicles two and three only showed slightly higher iron wear than vehicle one. Vehicle four was the only vehicle which had the factory-fill oil changed to AMSOIL synthetic gear lube, and despite significantly higher mileage than the first three vehicles, it showed a significantly lower level of wear. This test clearly demonstrates that the heaviest amount of wear occurs early in the break-in period. Wear is significantly reduced when the gear lube is changed to AMSOIL synthetic gear lube following the break-in period.

It Never Breaks Down in Your Driveway

AMSOIL Synthetic ATF and SEVERE GEAR Synthetic Gear Lubes Provide Maximum Protection for Severe Operating Conditions

There is much to be done before leaving for a vacation, not the least of which is proper vehicles maintenance. Most people are aware of the importance of changing their motor oil, but many people overlook the importance of changing the automatic transmission fluid and gear lube. Proper engine and drivetrain maintenance are equally important. After all, if the drivetrain fails, it doesn't matter how well the engine has been maintained. Nothing ruins a vacation quicker than becoming stranded in a remote area due to neglecting proper fluid maintenance.

Although many motorists consider their everyday driving habits to be normal, this is not always the case. In addition, some vehicles are subjected to extreme operating conditions such as snow plowing, hauling heavy loads and towing heavy trailers. These extremes put more stress on drivetrain components than just driving back and forth to work. New vehicles such as turbo diesel trucks and vehicles with V-10 engines boast more horsepower and torque than their predecessors, but differential designs have remained virtually unchanged. Differentials today are subjected to severe duty service and encounter more stress and heat than was seen only a few years ago. Modern gear oils are faced with the challenge of providing adequate wear protection during severe service operating conditions, while also providing maximum fuel efficiency.

Many people overstress their vehicles while on vacation. It is not uncommon to see vacationing families driving around in overloaded vehicles. The roof rack is filled with equipment, the back seat is filled with bags and the suspension is bottomed out. Some vehicles also pull trailers or fifth-wheels and boats, and some of these vehicles exceed their rated towing limits. As vehicle stress increases, transmission and differential temperatures rise and cause conventional lubricants to thin, causing inadequate lubrication that can lead to component failure.

Some vehicle manufacturers require the factory-fill differential gear lube to be changed within the first 3,000 miles, or the first 500 miles of towing, a fact not known by many consumers. Because differentials go through a break-in period and are not equipped with filters like transmissions and engines, the gear lube must be changed in order to drain the break-in wear particles. These particles, if left in the differential, mesh between the gears and cause gear or bearing wear or failure. Recent studies show that the most differential wear occurs in the first 5,000 miles.

AMSOIL Synthetic Universal Automatic Transmission Fluid (ATF) and SEVERE GEAR 75W-90 and SEVERE GEAR 75W-140 Synthetic Gear Lubes (SVG & SVO) provide maximum protection in demanding environments such as towing, hauling and commercial use, providing increased lubricant film protection and reduced wear at elevated temperatures. Synthetic ATF and SEVERE GEAR Synthetic Gear Lubes are formulated for extended drain intervals of up to 50,000 miles in severe service and 100,000 miles in normal service, or longer where specified by the vehicle manufacturer.

Yesterday's and Today's Differentials

The function of a vehicle's differential is to transmit engine power to the wheels, while allowing them to rotate at different speeds.

Differential design has evolved greatly since its conception. The first differential is thought to have been an early clockwork mechanism of Greek origin, and it can be traced back to around 87 B.C. The lubrication used for these gears is unknown, but because a lubricant of any kind may have changed the clock's timing, it is speculated that no lubricant was used. Most all branches of engineering owe something to clock making. For example, the thermostat in an oven, the chain drive of a dredger and the differential gear in the axle of a car were all first invented for clockwork.

Wooden cylindrical peg type gears lubricated with animal fat were used around 1200 A.D. for ship anchor hoists and catapult pre-tensioning. In 1872 Onesime Pecqueur of France installed the first differential gearing into a steam-powered machine. Pacqueur also invented and patented the first limited slip type axle. In 1870 James Starley, known as the father of the British bicycle industry, invented a tricycle with a differential gear, and the principle was used as the basis for the automotive differential. Automotive differentials incorporated worm drive gear sets lubricated with heavy petroleum oil until Packard introduced the modern hypoid differential in 1925.

The worm drive differentials used in early automobiles were unreliable and noisy. The introduction of hypoid gears solved the noise problem, but their sliding action increased wear. In order to extend gear life, lead-type extreme pressure (EP) additives were developed and added to gear lubes in 1930. However, because lead was determined to cause health problems, the lead-type EP additives were replaced by sulfur phosphorus EP additives in the 1950's. The sulfur phosphorus additives provided improved benefits and are still in use today.

Automotive and truck differentials were not always exposed to the extreme conditions seen today, and higher quality gear lubricants have become increasingly important as vehicles have changed and improved. Although differential designs and sizes have not changed much over the last 40 years, the operating conditions are very different.

Differential operating conditions have become increasingly severe through the years due to the following:

1) Less lubricant used

2) Up to 93 percent more horsepower

3) Towing limits increased from 7,500 to 18,000 lbs.

4) Air flow for cooling decreased in favor of increased aerodynamics

5) Smog systems require hotter running engines, generating increased air temperatures around the differential

6) Increased differential temperatures up to 300 degrees F

7) Increased interior room sacrifices air space for cooling around the differential

8) Exhaust pipes and mufflers pushed closer to the differential, increasing heat.

AMSOIL Synthetic Gear Lubes are specifically formulated to address modern differential operating conditions, providing extended drain intervals, long differential gear and bearing life and peace of mind.

New differentials go through a break-in period and should have the break-in gear lube changed after the first 5,000 miles to assure differential integrity over the life of the vehicle. AMSOIL Synthetic Gear Lubes provide superior protection and performance for differentials following the break-in period, saving motorists money through extended drain intervals, while also costing less per quart compared to many competing OEM gear lubes.

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