We asked leading fleet maintenance managers and the North American Council for Freight Efficiency for tips on how preventive maintenance can help improve fuel economy.

1. Use data to identify possible problems. “If we suspect a truck is having mpg problems, we will schedule it in for what we call a fuel economy check,” says Bill Bliem, senior VP, fleet services, for New Jersey-based NFI. “This includes valve and overhead adjustment, air filter minder check, alignment, fuel flow, etc.”

2. Take care of your tires. Maintaining correct air pressure in tires equates to fuel savings. For every 10 psi of under-inflation, a 10% reduction in fuel economy can result, according to NACFE. Improper wheel alignment can rob fuel efficiency by creating rolling resistance and also cause premature tire wear.

“The biggest thing we do maintenance wise and our biggest fuel economy pick up is tire pressure and alignment,” Bliem says.

3. Change your oil. Too little or too much engine oil can create more friction and rob power. Clean oil lubricates better than dirty oil, so pay attention to oil change intervals. Explore the use of lower-viscosity oils to improve fuel economy.

Gerry Mead, senior VP of maintenance for Chattanooga-based U.S. Xpress, recommends oil intervals based on your fleet’s operations. “OEMs set a limit, but is that limit good for your operation and type of oil?” he notes. “Oils break down and that takes away from its properties to cut down on wear. As oils break down they are less fuel-efficient. We have a zero overdue mentality.”

4. Let the engine breathe. A restricted air intake system (air filter, air cooler, and tubing) or exhaust system will decrease engine power output. Check components at regular PMs and fix any leaks. These leaks can be particularly hard to find, as leaking air is not as noticeable as fuel or oil, but their repair will improve engine operation and fuel efficiency.

5. Maintain air conditioning. The air conditioning compressor requires horsepower to operate, lessening the amount available to create and maintain forward momentum. An air conditioning system that is not operating near optimum efficiency requires even more power. Make sure the condenser and evaporator coils are clean and free from obstructions, the drive belt is in good condition, and the refrigerant level is at the proper level (too full is an issue too).

6. Maintain engine cooling fan. The main engine cooling fan requires a lot power to operate on today’s hotter-running, low-emissions engines. Ensure the fan clutch is operating correctly so the fan runs only when needed. A fan that runs constantly causes a significant reduction in economy.

7. Clean DPFs regularly. Clean diesel particulate filters improve fuel economy by about 2 to 3%, according to NACFE. Diesel particulate filter cleaning — Somewhere around 200,000 miles is a good time to clean these filters, but it does vary widely by engine/truck maker and duty cycle.

8. Maintain aero devices. That money you spent on aerodynamic trucks and trailer aero devices can be wasted if they’re not working right. Always maintain the aerodynamic panels and devices, whether they came with the tractor or trailer or are aftermarket add-ons. They won’t do their job correctly if they’re damaged. Replace or repair them as soon as possible.