History Guides Fleets’ Engine Oil Choices; Many Still Prefer Heavier-Weight Blends

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By Steve Sturgess , Special to Transport Topics

This story appears in the Jan. 26 print edition of Transport Topics.

Decisions about which engine oil fleets run in their trucks are based on everything from past experience to everyday convenience, but those choices can affect the long-term performance of the equipment, service and manufacturing representatives said.

The first decision often centers on whether to continue with what was poured into the crankcase at the factory or replace it with a favored choice.

“Most fleets use the factory fill for the entire first drain and then switch to their preferred brand,” said John Moore, manager of product marketing for Volvo Trucks in North America. “In most cases, fleets switch from the 10W-30 factory fill to 15W-40 viscosity, but some are looking at 10W-30 oils for improved fuel economy.”

Ratings such as 10W-30 and 15W-40 are measurements of the oil’s viscosity, which is broadly defined as its thickness or weight. For so-called “multigrade” oils, such as 10W-30 and 15W-40, the first number denotes how thin the oil gets in cold temperatures — when engines are harder to start and might need a thinner oil. The second number is its maximum weight, or how thick the oil would be in warmer conditions.

“Many truck owners tend to look at the viscosity grade as an oil-quality indicator, but it is not,” Moore said. “The oil’s specification is the indicator of performance, either the American Petroleum Institute specs or brand-specific specs. Those specs apply to both 30 weight and 40 weight oil. More fleets are beginning to consider 10W-30 for fuel economy, and the trend likely will continue as fleets start to exhaust other tactics to improve fuel economy.”

For some fleets, however, those ratings are about a lot more than fuel economy; they also affect all-around engine performance and economy.

“Two years ago, we did try a changeover in three shops to the lighter grade to see what would happen, but drivers noted that idle oil pressure was lower, [and] in some cases, we had low-pressure warning lamps,” said Kevin Tomlinson, maintenance director of South Shore Transportation Co., a flatbed truckload carrier based in Sandusky, Ohio. “Right now, we’re running 15W-40, but we are contemplating changing to 10W-30 for the economy benefits.”

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Moore believes more fleets should be open to this change. “In today’s engines, there is no reason not to use 10W-30, and the fuel-economy improvements are significant: somewhere between 0.5% and 1% in a lab but potentially 1-2% in a fleet operation where there is a lot of stopping and starting and temperature extremes,” he said.

And because Tomlinson is running some Volvo trucks, he is contemplating a change to the factory oil spec for the engines.

“We are running some new Volvos that come with a 10W-30 [first] fill,” he said. “Everything else is on 15W-40, [and] this makes things more difficult. One brand and barrel is my preference.”

Engine manufacturers have switched to the 10W-30 grade, partly in response to North American fuel-economy mandates for heavy trucks. And while fuel prices remained high, there had been a slow but steady move to the lighter, more fuel-efficient grade, said Dan Arcy, OEM technical manager for Shell Lubricants.

“Backward compatibility in new oil categories is the challenge. And while that has been met in the development of API’s CJ-4 oil category, the challenge will be to accommodate some of the lower-viscosity grades in the upcoming PC-11, particularly the 11(b), which is being developed for lubes such as 5W-30.”

Because that is not due till late 2016, it is not a concern today, but its introduction is likely to hasten fleet acceptance of lighter viscosities, Arcy said.

Manufacturers are aware of the preference among fleets for higher-viscosity grades, said Joe Scarnecchia, manager of national accounts powertrain sales for Mack Trucks.

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“In our experience, most fleets switch to their preferred brand and viscosity of engine oil after the first drain,” he said. “Some believe that different brands and viscosities result in better performance for their equipment.”

That’s true for Tomlinson, who said he generally relies on a single manufacturer’s lubricants for South Shore’s trucks.

“I’ve used it for a long time with good luck; never had an oil-related issue, and we run extended drains,” he said. Tomlinson extends the drain interval, under the engine manufacturers’ guidelines, to save on costs for the lubricant and the cost of disposing of the used oil, he said.

A history of good performance can justifiably be a strong indicator for fleets, but Scarnecchia noted that maintenance managers would do well to pay close attention to the oil’s ratings.

“The selection of engine oil brand and viscosity is likely based on [fleets’] preference or personal experience, but to be used in a Mack engine, the oil must meet our Mack EO-O engine oil specification, which is based on the API CJ-4 oil specification and designed for trucks equipped with engines meeting the 2007 and later emissions requirements,” he said.

Scarnecchia was referring to regulations enacted that year by the Environmental Protection Agency. Mack offers private-label oils in 10W-30 and 15W-40 viscosities that meet the spec.

Mack’s sister company, Volvo, has a similar spec.

“The oil for Volvo trucks must meet our Volvo VDS 4 specification,” Moore said. That standard also complies with the CJ-4 standard. Volvo also offers its own line of oils in 10W-30 and 15W-40 weights.

All oils used in modern diesels should meet the CJ-4 spec. Compliant lubes, with the API “donut” on the label, are available from all the major oil brands. And, Arcy said, when topping up oils, it is best to use the same brand and grade of oil but always use one that carries the API CJ-4 “donut.”

The CJ-4 specification was developed for use in diesels designed to comply with tiered emissions regulations that took effect in 2007. These dictated using a diesel particulate filter, and an oil reformulation was required to avoid plugging of the filter media. Starting in 2010, engine and truck manufacturers began adopting selective catalytic reduction emissions systems, which rely on an aftertreatment setup to convert nitrogen oxides, or NOx, into nitrogen and water.

Manufacturers also have long touted fuel-economy gains that SCR can deliver versus older engines. But proponents of using thinner oils also see fuel-efficiency gains.

“In most cases, fleets switch from the 10W-30 factory fill to 15W-40 viscosity, but some are looking at 10W-30 oils for improved fuel economy,” Volvo’s Moore said “On-road engines that comply with 2007 or newer EPA regulations have no problem with 10W-30 oils.”

“There seems to be a reasonable acceptance of the lighter viscosities,” said Darry Stuart, president of maintenance management consultancy for DWS Fleet Services and a past chairman of the Technology and Maintenance Council of American Trucking Associations. “I’ve tried it in a couple of fleets because of pressure from within the fleet to at least try.”

But measurable results have been elusive, he said.

“We really can’t measure the improvement in economy,” Stuart said, adding that fleets sometimes expect to save “millions of dollars” with the switch.

“In general, I run with whatever the fleet has decided to use,” he said. “With engines, it is whatever oil the fleet has settled on or whoever the best buddy is out there.”

Moore agreed that relationships with trusted service partners play a role. “The relationship with the local jobber probably has a lot to do with lubricant selection,” he said.

Mack’s Scarnecchia also agreed. “The relationship with your local service technician is definitely a factor,” he said.

“My opinion is that fleets switch to their brand and grade simply because that is what they have at their own shops,” said Steph Sabo, owner and president of Fast Truck and Trailer, a truck-repair operation in Benton, Illinois, and TMC member. “In the outside service world, our experience is that they prefer to run their typical brand and grade.”

But fleets take a risk when their trucks are serviced from the road, said Michael Stricker, manager of western region component technical sales for Daimler Trucks North America.

“If their terminals have 10W-30, [then] that is what the truck will be filled with,” he said. Customers who use outsourced service facilities might not have the same level of control, he said. “When or if the truck has an oil change at an outside facility, they won’t be able to control what type of product that is used.”

Fleets are less discerning when it comes to transmission and gear lubricants, Sabo said.

“When it comes to transmissions and axles, they really don’t care, just as long as it is synthetic,” he said

But in some cases, that can be risky, Stuart said.

“There is major pressure from the manufacturers of these really expensive automated transmissions to follow their recommended maintenance practices,” he said. “To an extent, they’re holding fleets hostage. With 500,000- and 750,000-mile warranties, you have to follow recommendations as the transmissions are so expensive, so a full synthetic of the grade as approved by the manufacturer is a wise precaution. It’s not like the old days with an Eaton when you ran the oil forever.”

Volvo’s I-Shift AMT has a 500,000-mile service interval, Moore said, and he noted that there aren’t as many choices for replacement transmission lubricants as there are for engines.

“Fleets are more likely to stay with that [factory] lubricant, but there aren’t as many products to choose from for automated transmissions as there are for engine oils,” he said.

They’re also likely to stay with axle lubricant for a truck’s entire service life, Stuart said. “The rear ends are generally left alone, and whatever the manufacturer’s spec calls for is used,” he said. “Progressive fleets don’t change the lube at all. Some of the ‘old dogs’ believe they should change, [but] they are basically in fear of warranty. You need only ever open up rear ends if there’s damage from abuse.”

Axle manufacturer Eaton Corp. said in a lubrication manual that the first fill is good for 500,000 miles in linehaul service. But there’s a lower mileage — 180,000 miles or three years — in vocational applications.

“Most axles for Class 8 trucks have synthetic lube, and drains are done using lubes that have Eaton or Meritor approval,” he said, mentioning two major manufacturers of drive axles. “Both manufacturers list the lubricants that [they have] approved at their websites. The 500,000 miles to drain for many OTR fleets means trading [the trucks] off without draining.”