Optimizing preventive maintenance (PM) schedules is a fine art. No one wants to jeopardize equipment by extending oil drains or servicing other systems prematurely, but then neither does anyone want to do servicing before it is necessary.

Making the most of maintenance dollars means intelligent planning and good implementation. Fleet Equipment talked with three successful fleet managers to learn how they optimize PMs. Here are our questions and their answers:

“For power equipment, linehaul, we are currently set at 20,000 miles,” says David Foster, vice president of field maintenance for Southeastern Freight Lines. “We are set at this interval because, for Southeastern, a linehaul unit is really a combo vehicle, which means it is being used in linehaul at night and P&D during the day. For our true P&D equipment, the mileage varies, depending on the engine model the unit is equipped with. At a minimum, we are greasing and inspecting these units every 90 days. However the oil is set to be changed anywhere from 7,000 to 10,000 miles or every six months, whichever comes first. Trailers are inspected and greased every 90 days or 10,000 miles, whichever comes first. “

Peter Nativo, vice president of maintenance for Transport Service Co., notes that the PM interval for tractors is set at 90 days or 30,000 miles. Nativo made this determination based on a three-year study he performed. He says it fit the company’s needs as a long haul carrier.

Darry Stuart, principal at DWS Fleet Management Service, says that his rule of thumb for Class 8 vehicles is PM intervals that are set at 25,000 miles or 120 days. For smaller vehicles, he recommends 7,000 to 10,000, or every 120 days.

“The interval is based on the quality of the PM, and the oil and grease is the cheapest part,” he says. “I do not try to extend beyond the limits of the PM. In special applications where there are PTO shafts, we grease them every time they come through the shop. I do not use oil analysis. Unless you are a chemist and do TBN checks, the rest is fluff.” For trailer maintenance, Stuart says the intervals vary from fleet to fleet, but basically it’s 90 to 180 days, no miles.

“We converted to long-life coolant a couple of years ago,” Foster says. “We have also been using oil analysis for some time and will be making some changes this year to our oil drain interval based on these results. We have also been evaluating fuel consumption records, and it is our intention to replace mileage intervals with fuel-consumed parameters.

Nativo states, “We use oil analysis, but only after the vehicle is four years of age or it has reached 400,000 miles. We determined that number (four years or 400,000) because of the extended warranties we receive on our engines, five years or 500,000. We are testing at four years, 400,000 miles, so we identify issues long before the five-year, 500,000-mile warranty expires.”

As Stuart mentioned previously, he does not use oil analysis. However, he does provide this caveat, “I will use oil analysis if I am looking for a specific problem. “I have used ‘long-life’ coolant all my life, put the green stuff in, take out the green stuff, put it back in, as well as all the other colors. It is all ‘long-life’ if you manage and use it correctly. The quality of the PM is the basis for extended PMs, not the oil. All of the oils are good, all of the greases are good, providing you perform the procedures correctly.”

Foster says that his fleet tries to time its PMs to be completed in conjunction with the annual federal guidelines.

Nativo adds that his fleet does a complete tire check and torques the wheels.

Stuart’s list includes: pressurizing the radiator, load testing the batteries, cleaning the terminals, aligning the front and rear axles, putting air in the tires, greasing the vehicle, changing the oil, checking all fluids, torquing the U-bolts and torquing the wheel nuts. In addition, he checks for air restriction, alternator output and assesses when to replace the belts and tensioners.

Foster states that, at this time, his fleet has no plans to purchase any power equipment in 2007.

On the other hand, Nativo says, “I started planning for this in 2002. I have changed my engine specification to include a Spinner II oil system to allow extended oil drain intervals. I do not intend to change my intervals in 2007 because of the Spinner II installed on our equipment. In 2007, all engine manufacturers will be installing a filter system on the engine breather. This will require another checkpoint for technicians during a routine PM on all 2007 engines.” He also notes that more information on this can be obtained from engine manufacturers.

Stuart contends, “I plan on no changes. I have been through all of these things before; the engine and oil people are far ahead of whatever I think I need to do. I still believe the basics are the most important things to consider. Find an interval, and be consistent.”

When asked for additional insights, Stuart adds, “there is more money saved in vehicle utilization than can be saved on quarts of oil, so figuring out how to keep vehicles on the street rather than in the shop is key. Optimization is the procedure and training, not time it takes for the PM. Using a detailed PM sheet, do lots of training. Technicians tend to fall back to their own personal practices unless you continue to follow up.”

Foster says, “I agree with Darry that training is key. This goes hand in hand with good communication and clear procedure given to technicians on what is expected of them during a PM, and how you want it completed. We work very hard to give our technicians the information, tools and training they need to perform maintenance tasks, including PMs. We also listen to our employees and have incorporated their ideas and feedback in everything we do. As a rule, the feedback we get from the floor is usually the best we can get. We publish the information as a Southeastern Maintenance Service Topic, which is distributed online through a fleet portal where all our associates have access to it.”

All three of these equipment managers clearly understand the importance of well established preventive maintenance programs. None of them leave anything to chance.

Optimization of PMs begins with the manager’s ability to assess the needs of the fleet, vehicles and drivers and do what it takes to protect assets and keep trucks up and running, providing revenue.