A Glance at Clean Freight Strategies:

Low-Viscosity LubricantsSynthetic engine and drive train lubricants can improve fuel economy by about three percent, saving nearly500 gallons of fuel and eliminating five metric tons of greenhouse gas emissions for a typical combinationtruck each year.

What is the challenge?Lubricants reduce friction and wear of critical vehiclesystems including the engine, transmission and drivetrain. Without lubricants, the moving parts insidethese systems would grind together causing heat,stress and wear. Conventional mineral oil lubricantsmay have too high viscosity (internal friction thatresists sliding and inhibits flow) to effectively slipbetween and lubricate the moving parts of thesesystems, particularly in newer truck components thatare designed with close tolerances and tight fits.Conventional lubricants may also be heavy, makingit harder for pumps, gears and shafts to move. Theseeffects create energy losses and friction losses, andwaste fuel. .

What is the solution?Low-viscosity lubricants are less resistant to flow thanconventional lubricants, a property that helps reducefriction and energy losses. Depending upon theapplication, low-viscosity lubricants may also containadditives designed to withstand the extreme pressure(EP) that could occur as the lubricant flows betweentight-fitting parts. Low-viscosity lubricants may bemade from synthetic or mineral oil blends with low-viscosity and EP additives. Manufacturers generallyoffer low-viscosity blends as “fuel economy”lubricants, since the fuel-saving potential of theseproducts is significant. A national trucking associationreports that synthetic transmission and axlelubricants can improve fuel economy by 0.5 percentin the summer and two percent in the winter(viscosity is temperature-dependent.) A paperpublished by a professional engineering societyfound that synthetic engine and transmissionlubricants could improve fuel economy by fivepercent, with greater gains at lower speeds. Anotherpaper from this same organization reports thatsynthetic gear lubricants can improve fuel economyby about three percent. European researchdemonstrates a three to five percent gain in truck fueleconomy using low friction engine lubricants and aone to four percent gain using low frictiontransmission lubricants.

Synthetic and semi-synthetic lubricants typically costmore than conventional mineral oil lubricants. Truckservice stations suggest that semi-synthetic oils costabout 50 percent more than conventional mineraloils. However, for most trucks, the fuel cost savingsgenerally outweigh the higher product cost.

The results are in . . . The combined effect of low-viscosity synthetic engineoils and drive train lubricants can improve fueleconomy by at least three percent, saving nearly 500gallons of fuel per year for a typical combinationtruck. Even with the higher cost of the synthetic oil,truck owners can save more than $500 per year.Additional cost savings may be possible due toreduced wear and maintenance. Switching to low-viscosity lubricants will reduce greenhouse gasemissions by five metric tons per year for each truck.

Next stepsTrucking companies should consider using low-viscosity lubricants to improve fuel economy.Synthetic oils are compatible with most trucksystems, save fuel, and should provide net costsavings. Before switching lubricants, truckingcompanies should ensure that the product suits theintended application. Always check manufacturerspecifications before switching engine, transmissionor drive train lubricants. Companies should alsoconsult manufacturer’s vehicle and parts ownermanuals and service manuals for information andrecommendations on lubrication specifications andprocedures. Lubricating oil manufacturers andlubrication guides can provide information aboutproduct applications. Trucking associations,equipment manufacturer associations and truckingindustry publications may provide additionalinformation and case studies about the benefits anduses of various lubricants.