Thin is in

Low-viscosity heavy-duty engine oils are beginning to get some attention as an easy way to improve fuel economy, while maintaining the protective qualities truck owners have come to expect from time-tested 15W-40 oils.

Since 15W-40 oils are the predominant type used in heavy-duty truck engines today, essentially any thinner oil can be characterized as low-viscosity engine oil. The most common would be 10W-30 and 5W-30 oils, which are available in conventional, semi-synthetic and full-synthetic variations from all the major suppliers.

Fuel savings of 1% have been proven when moving from 15W-40 to a low-viscosity 10W-30 engine oil, with some suppliers saying savings can reach up to 3% under certain operating conditions. The oils deliver fuel savings because they are thinner, requiring less energy to produce the same amount of horsepower as traditional 15W-40 oils.

Imagine swimming a lap in a pool filled with honey, compared to a pool containing water. Naturally, swimming in the honey-filled pool would require more exertion and would leave you more fatigued than a lap in the water-filled pool.

That’s how Jim Gambill, North American commercial and industrial brand manager with Chevron explains the benefits of low-viscosity heavy-duty engine oils. Because the oil is thinner, it provides less resistance and requires less energy from moving parts within the engine.

“Even a little change is important to fuel economy, since you are doing it 1,500 times a minute. The trick is to still be able to protect your equipment,” Gambill told Truck News in an interview, adding the newest low-viscosity engine oils are buttressed with strong soot dispercency and wear control.

Today, low-viscosity heavy-duty engine oils account for just 6% of the North American market. It’s expected that market will grow as fleets gain confidence in the protection offered by low-viscosity engine oils, and see the fuel savings for themselves. Extensive testing by multiple oil companies has shown low-viscosity engine oils are every bit as good at protecting the engine as their 15W-40 counterparts.

“When we tested our Duron-E 10W-30 versus our 15W-40 – the’re both conventional oils, the only difference is one is lower viscosity – we found the protection is the same for our 10W-30 as it is for our 15W-40,” said Jane Li, category portfolio manager with Suncor Energy, which markets Duron-E oils under the Petro-Canada brand.

Dan Arcy, OEM technical manager for Shell Lubricants, agreed that protection isn’t compromised when moving to a lighter-weight oil.

“We have done a lot of field testing with lighter-viscosity oils and we’ve shown basically the equivalent engine wear protection with our 10W-30 as with our 15W-40,” Arcy said, noting Shell did a complete engine teardown after 800,000 miles and found no difference in wear between engines running 10W-30 and those using traditional 15W-40 oil.

If you’re still not convinced a 10W-30 can provide the protection you’ve come to expect from a 15W-40, then consider it’s the engine manufacturers that are really driving the more widespread adoption of low-viscosity oils. All the engine manufacturers have now approved the use of low-viscosity engine oils, and some have even opted for them as factory fill. As the US Environmental Protection Agency pushes for improved fuel mileage out of heavy-duty trucks, it’s likely that engine manufacturers will continue to promote the use of low-viscosity engine oils as an easy way to improve fuel mileage by 1% or more.

That’s what JP Soucie, key account manager for Eastern Canada with Castrol distributor Wakefield Canada, believes will happen.

“It’s not a hard thing to predict as to where the EPA wants to go with fuel economy,” Soucie said. “The industry is going to move to low-viscosity engine oils because the EPA is going to mandate it.”

Chevron’s Gambill added: “The OEMs are now driven by the need to reduce greenhouse gas emissions and that’s why they are looking at these oils. We are one piece of their fuel economy tool set.”

None of the oil experts Truck News spoke to expect 15W-40 oil to become obsolete in the near future.

“I still think there’s a future for 15W-40 oil, and it still holds the majority of the North American market,” said Li. “Similar to what we’ve seen in Europe, the market will go to a low-viscosity oil, but I don’t think in the next 10-15 years that the 15W-40 will disappear.”

Shell’s Arcy said owner/operators, in particular, are likely to cling onto their 15W-40 engine oils, because it’s what they know and are comfortable with.

“I’d have to say from my discussions with owner/operators, they are more accustomed to and comfortable with using 15W-40 and I think there may be a little slower change within that segment of the trucking community,” Arcy said.

A 1% fuel economy improvement is most enticing when extrapolated over a sizeable fleet, and may not be reason enough to switch oils if you’re a one-truck operator. But there are other benefits to using low-viscosity engine oils as well, which can be appreciated equally by owner/operators and fleets of all sizes. One is the improvement in cold weather startability. Because the oil is thinner, it flows better in cold temperatures and reaches all the extremities of the engine more quickly than a thicker 15W-40.

“Also, Shell has done some testing to look at how much energy it takes to crank an engine over in cold temperatures and we’ve seen a significant reduction in the amount of energy and the amount of battery power it takes to turn the engine over when using 10W-30 versus 15W-40,” Arcy said.

That could mean fewer battery failures or starting issues in cold climates.

Another benefit is potentially longer drain intervals, provided, of course, they’re supported by an oil analysis program. Soucie said one large over-the-road Castrol customer has extended drain intervals to 113,000 kms, using a semi-synthetic 10W-30.

If you’ve decided to give low-viscosity engine oils a try, there is no shortage of options. They range from a conventional low-vis, to semi-synthetics right on up to full-synthetics in a wide variety of weights. Any change in oil type should first be approved by the engine manufacturer and should be made in consultation with the oil provider. Price points, too, vary widely, with full-synthetics costing up to $9 per litre. Still, Wakefield’s Soucie insists the pricier full-synthetic low-vis engine oils deliver the best value when total life-cycle costs are measured.

“You will see some fuel economy out of a conventional 10W-30, just because it’s thinner,” Soucie said. “But you will see more dramatic fuel economy coming from a mid-range product such as a semi-synthetic, because the formulation has been designed to accommodate fuel economy as one of the benefits.”

Soucie admits the Canadian trucking industry
currently has “no appetite” for full-synthetic low-viscosity oils, because of the sticker price, but that doesn’t stop him from singing their praises.

“Conventional oil is a cost of doing business,” he said. “A semi-synthetic lowers your total cost of operation because of labour and consumption savings. A full-synthetic – despite being in the $8/litre range – is the only oil that’s free. In fact, full-synthetic oil is the only oil that pays you back. The savings you receive from a full-synthetic oil supersede the costs of purchasing it, because you will get anywhere from 2-4% better fuel economy out of a full-synthetic.”

– This article appeared in the May issues of Truck News and Truck West

Truck News is Canada's leading trucking newspaper - news and information for trucking companies, owner/operators, truck drivers and logistics professionals working in the Canadian trucking industry.

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