by 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 avail- able 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, 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 metal-to-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.
Severe-service applications used for towing, hauling, 4x4 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 airﬂ ow 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.
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 OEM- recommended ﬂuid can get very expensive. A 2006 Dodge Ram 1500 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.
Contact Michael Sparks