When it comes to debating the cost-effectiveness of oil analysis programs, Charlie Yates takes the position that since fleets can't get inside their truck engines on a regular basis to see if something's wrong, the only way to get that “interior view” is to examine the oil that's been inside the engine.

”You use oil analysis to keep an eye on your truck,” explains Yates, director of field engineering for Castrol Heavy Duty Lubricants. “Take the new low-emission engines using EGR [exhaust gas recirculation], for example. That process can lead to higher soot loads in the engine oil. So will the oil last as long as you expect? The only way to really know is to take a sample and test it.”

Oil analysis is all about breaking down engine oil to its molecular level to see how it's holding up, i.e., to see if it's been contaminated by diesel fuel, soot, engine coolant or other foreign substance. The presence of any of those is an indication that something is going seriously wrong inside the guts of a truck, says Yates.

Most truck engines today have a sump valve, making it easy to get a representative sample of the oil. Oil samples are placed into plastic bottles, sealed, labeled and shipped to Castrol's laboratory, where a battery of tests is performed to determine whether contaminants are present and whether the oil's viscosity is holding steady.

Yates says it usually takes 48 hours to complete the tests. When problems are identified — iron and aluminum deposits, for example, which could signify excessive engine wear — the customer is notified immediately.

Traditionally, use of oil analysis has been confined largely to vocational fleets. “They must deal with heavy engine loads, on- and off-road conditions, etc. Their engine oil is exposed to much harsher environments, so they look at oil analysis as a way to get advance warning if something's going wrong,” Yates explains.

He says 85% of Castrol's vocational fleet customers use some type of oil-sampling technique, compared to less than 10% of its over-the-road customers and just 10% to 15% of owner-operators.

Oil analysis is cost-effective when the data generated enables a fleet to safely extend oil drain intervals without compromising the health of the equipment, Yates points out.

For example, in 2002 New Penn Motor Express decided to extend oil drain intervals on its linehaul Mack single-axle tractors from 24,000 to 36,000 miles. Used oil samples, taken at 18,000 and 36,000 miles, showed no significant increase in wear, convincing both Castrol and Mack that leaving the drain intervals at 36,000 miles would not create problems.

Oil analysis can also help keep rolling stock in prime shape, which is important should a fleet decide to hold onto its trucks for an extra year or two.

“We have one fleet customer running 30 to 40 trucks that does its own maintenance and follows a strict oil analysis program,” Yates says. “They used to sell their trucks at 750,000 miles, then decided to push them out to one-million miles.” Oil analysis showed that the fleet would be able to keep the trucks going for an extra 250,000 miles without raising maintenance costs significantly.

However, Yates hopes that this focus on mileage will actually disappear if more fleets use oil-sampling programs to bolster their maintenance methods.

“To really get a consistent picture of how an engine is performing, we need to start thinking in terms of gallons of fuel burned,” he explains.

According to Yates, one quart of oil lasts for about 70 gallons of fuel burned-depending on the quality of the oil, of course. Using that as a benchmark, fleets can develop what he calls “severity-based maintenance” to more accurately gauge the overall maintenance needs of their equipment.

“The more severe the operation, the more maintenance you need,” he says. “A good oil analysis program helps you make that determination. If you have a precise picture of how hard your engines are working, you can do a better job of managing the amount of maintenance they need. You won't over- or under-spend on maintenance, yet you can still preserve the health of your vehicles.”