With a fleet to manage and a bottom line to protect, you don’t always have time to research things like API CK-4 and FA-4 diesel engine oils. As we approach three years since the first license of new API Service Categories, it is important to highlight the most notable trends and opportunities available when using these modern oils.
The number one factor in fuel efficiency isn’t the condition of the truck; it’s what’s, or who, is sitting in the truck driver’s seat. A trained driver who’s driving to maximize fuel efficiency can reduce a truck’s fuel consumption by as much as 35% versus drivers with less skill. That’s thousands of dollars a year per driver. A training program for your fleet could easily pay for itself in a matter of months with clear bottom line improvements for your annual budget.
Yet, there is so much more to it than the driving aptitude of your operators. You must consider technology, tires, trucks, and more. Let’s dig a little deeper into each of the factors that govern your fuel-saving strategy.
Cost and Good Driving Habits
As we mentioned, good driving habits are probably number one, but what do those include? Good driving habits include:
- Consistently maintaining the posted speed limit and using cruise control in permissible conditions.
- Applying gas and brake pedals smoothly and steadily.
- Changing gears at the lowest RPM.
- Coasting downhill when possible.
Since drivers are often the biggest “X-factor” in fuel-efficiency, establishing good driving habits with a fleet is imperative. As we mentioned, proper training can make a huge difference, but so can a little common sense and focus on proper driving technique. Reviewing the basics with your truck drivers on a regular basis can instill the proper habits in their day-to-day driving—and your day-to-day fuel savings.
A truck driver can also increase fuel efficiency by limiting unnecessary:
- Idling
- Gear shifting
- Cab accessories that can cause energy drain
The EPA also cites numerous factors that raise fuel costs, including:
- Engine idling, which can waste a gallon of fuel every hour.
- Driving 65 mph instead of 55 mph, which can increase fuel consumption by as much as 20%.
- Driving with a higher engine RPM, which can burn several extra gallons per hour.
Fuel Efficiency and Driveline Design
Since Rudolf Diesel first developed his engine, subsequent designers have tried to improve its efficiency. Those original diesel engines only converted about 26% of the fuel into usable energy for the vehicle. By the early 2010s, engine design had improved enough that they converted up to 44% of that fuel for energy.
Heavy-duty diesel engine designs have become 6% more efficient from 2010 to 2017. Some engine manufacturers predict that they can reduce fuel consumption another 15% by 2030—much higher than the EPA’s guidelines for that timeframe.
More efficient engines, increasing popularity of automated manual transmissions, improved cruise control systems, and idle reduction systems have all combined to provide better fuel economy than ever. In a recent trial conducted by NACFE, trucks in the test averaged better than 10 MPG—a number that would have been unthinkable just a decade ago!
Upgrading your fleet’s tractors on an annual basis doesn’t make fiscal sense for most. That said, there comes a point where the cost savings in fuel on a newer engine will offset or improve on the expense of purchasing that engine. Make an annual comparison of your fleet’s fuel consumption with that of the latest, most fuel-efficient engine/transmission combinations to know when a transition makes sense.
Fuel Efficiency and Tires
In general, a tire that has more surface area offers more rolling resistance. The more rolling resistance a truck needs to overcome, the more fuel it takes to reach and maintain speed. This is especially important in the drive and trailer positions, which account for more than 85% of rolling resistance.
Two main factors increase a tire’s surface area regardless of positions: heavy loads and tire tread. And when it comes to tire tread, there are a few things to consider: tread compound, tread design, and tread depth.
These are often related to one another—for instance, a softer compound will decrease tread depth faster—so they’re all important factors when selecting tires for your fleet. But they aren’t the only factors that can make tires more or less fuel efficient. Correct inflation pressure and proper alignment are both essential, too.
Fuel Efficiency and Aerodynamics
Trucks are not sports cars. They’re designed to haul heavy loads, not cut through wind. Because of that, there’s only so much you can do to reduce the drag on the vehicles in your fleet. You want to do as much as possible, though, because this aerodynamic drag is the cause of more than half of a truck’s fuel consumption.
There are four areas on a tractor-trailer where you should focus your efforts in making them more aerodynamic:
- Using an air deflector on top of cabs that matches the trailer height minimizes drag and begins to maximize fuel economy.
- If you can find a device that covers this gap completely, you can reduce drag by more than 5%.
- Side skirts can reduce drag enough to save up to 7% on fuel costs.
- Boat tail devices can save more than 6% on fuel costs.
The key is to combine these technologies for maximum fuel efficiency. By themselves they make a difference in fuel consumption. Together, they can make a significant difference.
Fuel Efficiency and Engine Oil
Just like air resistance is an external factor that impacts how hard your engine needs to work, engine oil is an internal factor on engine efficiency. Thicker, more viscous oils experience more internal fluid friction thus requiring more power—and as a result, more fuel—to cycle them through the engine.
Today’s engines run at higher temperatures due to higher power densities, improved aerodynamics, and modern emission systems. This increases the need for enhanced thermal stability and oxidation control in your oils. Further, these modern engines are designed to benefit from the use of a lower viscosity versus those from even ten or fifteen years ago. Every major North American engine builder has been factory filling with SAE 10W-30 for at least the last 6 years (most use API CK-4 10W-30 with Detroit Diesel utilizing API FA-4 10W-30).
If your fleet still runs on SAE 15W-40, we recommend you consider switching to API CK-4 10W-30 or FA-4 10W-30 diesel engine oils. CK-4 10W-30 oils can provide about 1% fuel economy improvement versus 15W-40 while FA-4 10W-30 can provide 1.5% improvement.
It’s important to note that API FA-4 oils must pass all the same performance tests (at the same levels) as CK-4—but with lower HTHS values. When two oils have the same kinematic viscosity (CK-4 10W-30 / FA-4 10W-30), the one with the lower HTHS value (FA-4, by definition) will have lower internal fluid friction which is what provides the fuel economy gain.
The Bottom Line on Fuel Savings
Look at every training opportunity, piece of equipment, and maintenance upgrade to keep your fuel costs as low as possible. For the most fuel-efficient diesel engine oil, work with your local supplier. During that conversation, make sure to tell them about your typical duty cycles and maintenance goals, so they can help you find the best balance for your specific equipment mix.
The fact is, with business costs on the rise across so many sectors, can your fleet afford to not get the most out of your vehicles’ fuel economy? Likely not. And with technology, oil standards, and so much more serving as aids in your attempts to get the most out of your fleet, there really is no excuse.
One area where you can get the most out of your vehicle’s fuel is with green technologies. While retrofitting trucks with fuel-saving specs can be a game-changer, going all the way to brand new can yield sizeable savings. Fleets can save a lot of money by upgrading old, fuel-slurping trucks. There are a lot of advantages to having a fuel-sipping fleet, with saving money being just one of the big ones.
When it comes to reducing fuel spend, it should be more about controlling the gallons than the cost of fuel. The cost will be what it is, whether you buy fuel wholesale or retail. Now you just need to take these factors into account and turn your fleet into a fuel-saving masterpiece!