Alan Amatuzio | EXECUTIVE VICE PRESIDENT / CHIEF OPERATING OFFICER
Automakers continue building vehicles that produce substantially more horsepower, torque and towing capacity than their predecessors, yet the gears and bearings responsible for converting this increased power into wheel rotation remain largely unchanged. To reduce drag and improve fuel economy in some vehicles, engineers have also reduced the volume of gear lube available to cool and protect. The 1996 Ford F-250 Crew Cab, for example, features a 10,500-lb. maximum towing capacity using a rear differential that holds 3.75 quarts of gear lube. The 2011 Ford F-250 Crew Cab, meanwhile, boasts 14,000 lbs. of maximum towing capacity despite a rear differential with a smaller, 3.45-quart capacity.
Increasingly, synthetics are relied upon to meet these higher demands. Some manufacturers now recommend synthetics in the differentials of certain newer vehicles, such as the Chevrolet Silverado and Ram pickup. The heightened awareness of synthetics presents AMSOIL Dealers with great sales opportunities, especially when considering other lubricant manufacturers spend little effort marketing their gear lubes.
Increased Wear Resistance
Differential designs come with inherent suffering points, and it’s here that synthetics prove their worth. In a traditional automotive differential (Figure 1), the input pinion gear concentrates intense pressure on the ring gear, forcing it to turn the side and spider gears. As all the gear teeth mesh, they slide against one another repeatedly, separated only by a microscopic film of lubricant. The constant stress the lubricant film bears can shear lesser gear lubes, causing permanent viscosity loss. Once sheared, the fluid film weakens, ruptures and allows metalto- metal contact, leading to increased friction, accelerated wear and eventual gear and bearing failure.
The composition and characteristics of synthetics play a vital role in wear reduction, an area in which AMSOIL synthetic gear lubes excel. Conventional lubes formulated with viscosity index (VI) improvers shear more readily under stress. AMSOIL synthetic gear lubes, however, maintain viscosity better than other conventional and synthetic gear lubes despite rigorous use and contain advanced anti-wear additives for further protection.
Extreme-Pressure Additives
Severe-service applications used for towing, hauling, 4×4 off-road driving and commercial use place even greater stress on gears and bearings. Many drivers operate under severe-service conditions without even knowing it. The sliding motion and pressure on gears can wipe the lubricant away, particularly in spiral-cut hypoid gears. AMSOIL Severe Gear® Synthetic EP Gear Lubes contain extreme-pressure (EP) additives that form a durable iron sulfide barrier on gear and bearing surfaces to guard against metal-to-metal contact in the harshest driving conditions.
Increased Operating Temperatures
Differentials have always run hot, but increases in power and torque coupled with reduced fluid volume and reduced airflow due to improvements in vehicle aerodynamics only worsen the problem. Testing has shown applications simulating trailer towing at 88 km/h (55 mph) at a 3.5 percent grade can experience differential temperatures as high as 188ºC (370ºF). Those readings could be even higher using today’s more powerful vehicles.
Thermal Runaway
As temperatures in the differential 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.
Here again AMSOIL synthetic gear lubes outperform conventional gear lubes. Not only do they resist viscosity loss due to mechanical shear, they resist thinning at high temperatures better than conventional lubes. In addition, the deposits conventional gear lubes leave behind coat gears and bearings, inhibiting heat transfer and shortening their life spans. What’s more, the lubricant thickens, increasing internal drag and reducing fuel economy.
AMSOIL synthetic gear lubes, however, are engineered in a lab and contain only uniform molecules less prone to volatilizing at high temperatures. As a result, they not only resist thinning in heat to provide better cooling and protective properties, they stay fluid in cold weather to ensure immediate start-up protection. Their uniform molecules also reduce friction, effectively reducing drag and increasing fuel economy.
Extended Drain Intervals
Following the original equipment manufacturer (OEM)- recommended differential drain interval using the OEMrecommended fluid can get very expensive. A 2006 Dodge Ram 1500 (see example below) requires a differential fluid change every 15,000 miles if driven under severe-service conditions, which includes towing, short trips of less than 10 miles and use where temperatures are below 32ºF. AMSOIL Severe Gear Synthetic EP Gear Lube is recommended for 50,000 miles in severe service. Its use in this example saves over $220. In addition, synthetic gear lubes recommended by OEMs are often more expensive. The lower cost of AMSOIL synthetic gear lubes combined with their extended-drain capabilities and superior performance and protection make them the ideal choice.
AMSOIL SYNTHETIC GEAR LUBES
Severe Gear® Synthetic EP Gear Lube
Specifically engineered for high-demand applications, including trailer towing, heavy hauling, 4×4 off-road driving, commercial use and racing. Superior film strength combined with extra additives protects gears and bearings from scoring and wear. Resists high heat and possesses excellent cold-flow properties. Outperforms conventional gear oils. Recommended for all types of vehicles such as turbo-diesel pick-ups, SUVs, autos, trucks, heavy equipment and motor homes. Compatible with most limited slip differentials.
Long Life Synthetic Gear Lube
Specifically engineered for drain intervals up to 500,000 miles as set by equipment manufacturers for over-the-road trucks. Protects against wear and improves equipment life. Excellent all-season summer and winter performance. Outperforms conventional gear oils. Also excellent for passenger cars and trucks. Compatible with most limited-slip differentials.
Synthetic 80W-90 Gear Lube
High-quality replacement for applications specifying SAE 80W-90 conventional gear lube. Synthetic construction provides improved cold-flow properties, high viscosity index, high heat resistance and excellent wear protection.
Severe Gear® Synthetic Racing EP Gear Lube
High-viscosity, extreme-pressure gear lube engineered for the demands of severe racing conditions, including off-road truck racing, rock racing, rock crawling, tractor pulling, funny car racing and dragster racing. Protects gears from shockloading and tire shake. Resists sling-off from G-forces and high speeds. Effectively clings to gears, promoting cooler operating temperatures and extending gear and bearing life.