Motor Oil Info

Automatic transmissions have become increasingly complex as vehicle manufacturers strive to improve efficiency while satisfying consumer demands. Smaller, smoother-shifting transmissions with longer fluid life capabilities and heavier load capacities are now standard. Traditional Automatic Transmission Fluids, however, are unable to meet these extreme requirements, and new fluids have emerged with each new advancement in transmission engineering. AMSOIL, with its original introduction of a synthetic ATF in 1980, remains the leader in transmission fluid quality.

AMSOIL Synthetic low-Viscosity Automatic Transmission Fluid is formulated with the highest-quality components to exceed the most stringent industry standards. Low-Viscosity Automatic Transmission Fluid is a fuel-efficient fluid, it has demonstrated its ability to protect as well as or better than higher-viscosity fluids in the most severe industry tests.

The rotating motion of the gear sets also tends to churn the lubricant, resulting in foaming. If a gear lube foams, the load carrying capacity is significantly reduced because the air suspended within the oil is compressible. For example, when the gear teeth come into contact with each other any trapped air bubbles will compress, therefore reducing the thickness of the separating oil film. In turn, this reduction could lead to direct metal-to-metal contact between gear teeth and result in accelerated wear.

The gear lube must have the ability to dissipate this entrapped air, insuring sufficient lubricating film exists to protect the gears from contact wear. Much like engine oil the chemical compounds, or additives, added to drivetrain stocks either enhance existing properties or impart new ones.

Because many of the components found in the drivetrain consist of ferrous material, the lubricant is required to prevent rust and possible corrosion to other materials. Rust and corrosion problems are not nearly as prevalent in engines.

The many small and intricate components that make up gear sets found in the drivetrain can be quite noisy and may be subjected to shock loading. The viscosity and extreme pressure formulation of gear lubes quiets gears and dissipates shock loading.

Motor oil has to combat byproduct chemicals from gasoline or diesel ignition and should contain additives such as detergents and dispersants. Since an internal combustion engine has an oil pump and lubricates the bearings with a hydrodynamic film, the need for extreme pressure additives such as those used in gear lube does not exist in engines.

Engine oils and gear lubes both have anti-wear additives, they both must lubricate, cool and protect components, but gear lubes are placed under extreme amounts of pressure, creating a propensity for boundary lubrication. For example, differentials in cars and trucks have a ring and pinion hypoid gear set. A hypoid gear set can experience boundary lubrication, pressures and sliding action that can wipe most of the lubricant off the gears. To combat this extreme environment , extreme pressure additives are incorporated into the oil . AMSOIL uses an extra treat of extreme pressure additives in its gear lubes in order to reduce wear and extend the gear and bearing life.

High quality gear lubes must lubricate, cool and protect geared systems. They must also carry damaging wear debris away from contact zones and muffle the sound of gear operation. Commonly used in differential gears and standard transmission applications in commercial and passenger vehicles, as well as a variety of industrial machinery, gear lubes must offer extreme temperature and pressure protection in order to prevent wear, pitting, spalling, scoring, scuffing and other types of damage that result in equipment failure and downtime. Protection against oxidation, thermal degradation, rust, copper corrosion and foaming is also important.

Gear lube is very different from motor oil. Most people assume that SAE 90 gear lube is thicker than 40 or 50 motor oil, however they are the same viscosity. According to AMSOIL Technical Drivetrain Products Manager Kevin Dinwiddie, the difference is in the additives.

Some manufacturers recommend changing the factory-fill gear lube within the first 500 to 3,000 miles based on SAE test stand and field tests. AMSOIL recommends the factory-fill differential gear lube be changed no later than the first 5,000 miles, even when vehicle manufacturers do not specify to change the factory-fill gear lube to remove wear particles.

When using AMSOIL synthetic gear lubes, AMSOIL recommends drain intervals of 50,000 miles in severe service or 100, 000 miles in normal service, or longer if stated by the OEM. AMSOIL synthetic gear lubes not only offer second-to-none protection and performance in cars and light trucks, including turbo diesel pickup trucks, they are much less expensive than OEM synthetic gear lubes. Changing break-in wear particles out after the first 5,000 miles of service and using AMSOIL synthetic gear lubes at the correct recommended gear lube drain interval ensures long, trouble-free differential life.

Transmission run hot , often leading to transmission fluid oxidation, causing clutch glazing and deterioration in shift quality. Clutch glazing can be felt as an elongated, slipping or sluggish shifting feel, and it’s usually a precursor to transmission failure. AMSOIL Synthetic Universal Transmission Fluid (ATF) provides maximum protection against oxidation and clutch glazing.

Although differential designs have remained relatively unchanged over the past 30 years, their operating environments have changed drastically. Modern differentials are subjected to as much as 93 percent more horsepower, towing limits up to 18,000 lbs, extreme operating temperatures and decreased fluid volume.

The subject of proper engine maintenance has plenty of attention in the media, and most motorists are aware of its importance to the reliability and life of a vehicle. If the vehicle’s engine stops working, a motorist is stranded. Very little attention, however, has been given to the stresses encountered by a vehicle’s transmission or differential. Transmission and differential maintenance is just as important as engine maintenance. After all, if the transmission or differential stop working, the motorist is equally as stranded.

Only a few years ago, the standard automatic transmission was a three speed. Today four, five and six speed transmissions are common, and one manufacturer produces an eight speed transmission. Modern transmissions and differentials are subjected to more horsepower, higher towing limits and hotter temperature extremes, and they contain more clutches and are subjected to additional shifting for the same driving speeds. Wear protection and oxidation resistance, therefore, are more important than ever. AMSOIL Synthetic Automatic Transmission Fluid (ATF) provides excellent wear protection required for the GM DEXRON III and VI specifications and it resist oxidation two times longer than required for conventional automatic transmission fluids.

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, Calif. 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 110 degrees F in the new axle and 95 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 the new axle and 295 degrees F with the broken-in axle.

AMSOIL Severe Gear 75w-90 and 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 lubricant’s inability to control friction and increased heat under high stress conditions.

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 lower 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.”

Most differential wear occurs during the break-in period. Because 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 trailers cause additional stress to the differential during the break-in period and can cause premature differential damage. Changing the gear lube after the break-in period (about 5,000 miles) greatly reduces wear and extends differential gear and bearing life. Auto manufacturers are beginning to recognize the importance of drain abrasive break-in materials. Some manufacturers recommend an interval of between 500 and 3,000 miles. The best way to go, is to replace your gear lube with Synthetic Gear Lube.