This story appears in the April 1 print edition of Transport Topics.
Engine-oil drain intervals are generally lengthening as lubricants and engines improve, but fleet managers still face the dilemma of whether to extend replacement timeframes to make their trucks more productive or remain conservative to protect their equipment.
It is a choice that has no single best answer, according to lubricant suppliers.
“We have customers that go only as few as 10,000 miles and other customers that can go 75,000 miles on a drain interval. It could be the same oil — even the same engine — but just a different type of service or load. It’s pretty wide,” said Shawn Ewing, technical coordinator of heavy-duty lubricants for Houston-based Phillips 66 Lubricants.
Tony Negri, director of marketing for commercial lubricants at Phillips 66, said he has seen some remarkable sophistication in the types of onboard technology some fleets employ in monitoring what happens to the oil on the road. This technology includes satellite tracking and diagnostic capabilities, among other useful tools.
“They are measuring and quantifying everything that they can. And for fleets like that, they are using oil analysis as a predictive tool. So rather than just doing spot analysis, they have trend analysis that they can look at,” Negri said.
Still, the general trend appears to be moving toward longer drain intervals, thanks to cleaner fuels; oils that can better manage acids, soot and other contaminants from the combustion process; and engines designed with larger oil sumps that allow for circulation of more oil.
But the improvements don’t completely eliminate problems such as soot and thickening viscosity.
“Even in today’s most advanced engines, which run on ultra-low-sulfur fuel, soot can have a significant impact on engine performance,” said Jane Li, transportation category portfolio manager for Petro-Canada Lubricants, based in Mississauga, Ontario. “In fact, as engine loads get heavier and drain intervals are extended further, the relevance of soot has never been greater.”
Incomplete combustion of diesel-fuel products creates soot that accumulates in the oil and can create sludge if the particles are not properly dispersed, industry experts said.
If a fleet does choose an extended drain interval, lubricant vendors strongly recommended that it be done with proper oil analysis and correspond with the engine maker’s original oil-drain guidelines.
Oil analysis can give fleets “a picture of the science behind optimizing oil-drain intervals,” said Maria Burcham, commercial vehicle lubricants products technical advisor for ExxonMobil Fuels, Lubricants and Specialties Marketing Co., based in Fairfax, Va.
“The idea being that, by monitoring the condition of the oil, you can monitor the condition of the engine, which is the critical piece,” Burcham said.
However, a carrier spokesman warned against adopting unnecessary processes and equipment — such as a “hydrogen generator.”
“I get calls weekly from people who have a new hydrogen generator that’s going to save us a fortune, but the advances on lubes seem to be the real deal,” said Paul Higgins, director of fleet maintenance, Prime Inc., which is headquartered in Springfield, Mo.
Prime is a refrigerated, flatbed and tanker carrier that ranks No. 23 on the Transport Topics Top 100 list of the largest U.S. and Canadian for-hire carriers. The company has more than 5,000 company drivers, plus some independent contractors.
Higgins said Prime sticks very closely to the manufacturer’s recommended drain intervals. The fleet’s Detroit Diesel 13-liter and 15-liter engines are drained and refilled at 50,000-mile intervals, and its Cummins ISXs are drained at 35,000 miles. He said he wants to do as many PM (preventive maintenance) services at one visit as possible — including oil changes at 35,000 or 50,000 miles; crankcase filters at 125,000 miles; and clutch/throwout bearing lubes at 25,000 miles.
Higgins said a computer system triggers a message to drivers and management when date-driven preventive maintenance is due within 30 days of tractor or trailer annual inspections and within 50 hours for auxiliary power units and reefer PM schedules — or, in other cases, within 2,000 miles of when mileage-driven PMs are due.
Stede Granger, original equipment manufacturer technical manager for Houston-based Shell Lubricants, said that, as a rule of thumb, the telltale markers that signal it is time to replenish the oils vary with the model year of the engine.
“Maybe in these newer engines, we would be looking at oxidation — or the breakdown of the oil due to high temperatures — as being the condemning limit. That’s not an immediate breakdown. It’s more of a gradual process that can accelerate at the end,” he said.
Granger also said viscosity thickening is something to look at, calling it a very simple thing that oil analysis can easily identify and could be related to soot or oxidation.
A fleet needs to understand its engine specifications, the actual operational demands and what management needs from the equipment, said Tim Moore, vice president of maintenance at the Watkins Group, which is based in Lakeland, Fla., and includes Sunco Carriers Inc. and Land Span. Watkins has about 500 power units and 1,200 dry and refrigerated trailers, as well as a separate bulk division called Highway Transport, in Knoxville, Tenn.
Moore said he always has been very conservative in pushing out drain intervals — and he tests chassis grease as well.
“It would not do the fleet any good if it had the world’s best extended oil-drain interval, but it was wearing out all its brake cams and slack adjusters because the grease won’t hold up. It’s really a delicate marriage with all of them. Obviously, the lubricant guys have done a really, really good job with synthetic gear lubes and transmissions. We now can get that extended interval there,” he said.
Fred Gebhardt, director of maintenance at Carbon Express in Wharton, N.J., said his carrier operates 45 tractors and transports bulk liquid chemical products across the United States and into Canada and Mexico. He said he is so confident about the level of his lubricants that the drain-interval process can be as simple as picking an oil and then doing your sampling.
“I think all the lubricants in all areas have come a long way. We don’t put a lot of time into it until there is failure that occurs — and then you look into what actually caused the failure. Was it a breakdown of the lubricant? The coolant? The grease?” Gebhardt said.
“If it comes to light [through used-oil analysis] that the oil actually broke down too early, then we would change the interval. But that is very rare,” he added.
Higgins said that it previously was not a concern whether an operator changed oil early or late — the engines always were covered under warranty.
“Nowadays, we get a daily report of any truck overdue, and we sometimes withhold dispatch until the PM is done,” he said.
Higgins added that Prime does not run fully synthetic engine oils. It does, however, use a version of 10W30 oil that is partially synthetic. Higgins also said he expects that version of 10W30 to provide about a 1% improvement in fuel mileage compared with his current 15W40 oil.
“It seems to make sense to us, but we’ve not done any fuel-economy testing to verify,” he said. “But my compadres in the business who have tested tell me it’s true. And it seems to make sense there’s a gain available simply because of the lower viscosity.”
Shell’s Granger said some engine makers are now allowing 10W30 to be used year-round, even in the summer when high ambient air temperatures can speed up the breakdown of an oil.
“That part is new. But some have some stricter requirements than the CJ4 [current oil spec] for 10W30. So, only certain 10W30 oils will meet those requirements. We think to meet those requirements, the oil might have to be a semi-synthetic or synthetic,” Granger said.
Higgins said Prime does run synthetic fluids in its transmissions and rear ends, however, “and since we only keep our trucks to 600,000 miles, we don’t have to change those fluids. We also run extended-life coolant, and the only maintenance is putting in extender.”
Moore said that when it comes to coolants, all the new trucks Watkins purchased the past two times came with extended-life coolant, which he manages by taking the advice of American Trucking Associations’ Technology & Maintenance Council, which fosters cooperation among designers and manufacturers of transport equipment and the fleet personnel who specify, purchase and manage that equipment.
“With a lot of my philosophies, policies and procedures, I follow the TMC and tend to lean a lot toward the recommended practices,” he said.
Moore also said some of his trucks have selective catalytic reduction technology to help manage emissions with diesel exhaust fluid.
“We haven’t had a need to drain it or flush it, but there is a filter in there that you want to make sure is part of your preventive-maintenance program,” he said.
Petro-Canada’s Li said that if fleets are anticipating using natural-gas powered engines, they will need another type of oil designed especially for that operating environment.
“Generally, with diesel engines the main concerns are effectively handling the soot and acids generated by the combustion of diesel,” she said. “Natural-gas engines are different. They are sensitive to the specific ash level of the engine oil, and generally they need lower ash than diesel engine oils. And they operate at much higher temperatures than diesel engines, meaning the oils need to be formulated to withstand high rates of oxidation and nitration.”
Li added, “The two engine types are different enough to require unique lubricants designed for each application.”
Alexis Smith, heavy-duty associate brand manager for Castrol Heavy Duty Lubricants, which is based in Wayne, N.J., and is a unit of British Petroleum, said that with the changes coming in diesel engines in 2016, heavy-duty engine oils will be split into two groups.
The new oil, Proposed Category 11, is being readied for the next generation of medium- and heavy-duty engines that must reduce their greenhouse-gas emissions and improve fuel economy to meet federal regulations set to be phased in model years 2014 to 2017. PC-11 will probably include improvements in oxidation stability and shear stability, resistance to aeration and use of biodiesel fuel, according to industry reports.
“One engine oil will be compatible for older engines and one engine oil for new engines. That will create some confusion in the trucking industry. With this change, oil formulations will need to be more specialized and less market general,” he said.