Flowing through the big, powerful engines of work trucks are substances of little comparative size but great might: fluids. Fluids are key to maintaining the health of a fleet; oil keeps the engine lubricated, coolants moderate temperature, DEF reduces emissions, and additives ensure peak performance.
Find out if your fluid knowledge is current as we answer the fundamental fluid questions.
Part one of the three-part series on truck fluids is all about oil. Not only is oil critical to engine health, it’s also an ongoing fleet expense. Making the right choices about which oil to use, when to change the oil, and using the right filter can help fleets strike the appropriate balance between cost and operating a well-oiled fleet (literally).
Which Oil is the Right Oil?
If you want a simple answer, it’s this: Use the oil recommended by the OEM.
“The No. 1 fundamental about oil is to understand the oil requirements for each vehicle’s engine,” said Stede Granger, OEM technical services manager for Shell Lubricants. “Your OEM representative or their website and your owner’s manual are good sources of information to be sure you’re choosing the right oil.”
Although the recommended oil may be a little pricier, Michael Middleton, core services manager, customer experience for Valvoline Instant Oil Change, said avoiding the temptation to use a lower grade oil actually pays off.
“Understanding the requirements from the manufacturer that the oil must meet is critical to ensure proper functionality for the truck. Don’t try to cut costs on using a lower grade oil,” Middleton said. “Work trucks are just that — work trucks. Giving them an oil that can meet the high demands on a work truck will benefit them in the long run. Fewer engine problems means less money spent on repairs and less downtime for a work truck off the road.”
But, let’s say you’re looking for an oil that can be used across a number of models in your fleet. In this instance, according to Granger, it’s important to be mindful of fuel type.
“In general, there is a difference between the oil used for diesel and gas engines. You don’t want to use gasoline oil in a diesel engine,” he said. “But, sometimes you can use diesel oil for both engine types. For mixed fleets with both diesel- and gasoline-powered trucks, it can be easier to use one engine oil fleetwide.”
It’s important to work with your lubricant supplier and OEM to help you identify the oil that offers the best performance for your engines, Granger said.
Scott Killips, CEO, HUBB Filters, said fleets can choose from a wide range of oils that are suitable depending on the specific application.
So, how should fleets narrow it down?
“Choosing an oil that is API-certified will help ensure that the oil will perform as advertised,” Granger said.
Killips also said proper engine lubrication is about more than what oil you choose.
“It’s not just the oil; it’s the oil and the oil filter because they work together in the vehicle’s lubrication system,” he said. “Compare it to the human body where the kidneys filter the impurities in the blood. In both cases, they work together and one can hold the other back if it does not function the way it should.”
Oil for Alt-Fuel Trucks
Alt-fuel vehicles may have slightly different oil requirements, according to Dan Holdmeyer, industrial and coolants brands manager for Chevron.
“Briefly speaking, switching to compressed natural gas (CNG) or liquefied natural gas (LNG) may require an engine oil designed to handle the higher temperatures generated and the engine modifications made to run those fuels,” he said. “Switching to a biofuel will require specific fuel system maintenance and potentially fuel additives tankside, depending on the level of biofuel but check with your fuel supplier first.”
What Do Oil Numbers Mean?
A common misconception about oil is the numbering system for viscosity grade, Granger noted.
“When people see 5W-40, they often think the ‘5’ means it’s too light for a work truck engine, but that number doesn’t indicate how well the oil is lubricating the bearings. The number on the left actually tells how well the oil performs in cold temperatures,” he said.
When it comes to the number before the “W,” think “winter,” not “weight,” because that number on the left represents the oil’s maximum viscosity or flow at a low temperature. The lower the number, the better the truck will start in colder temperatures.
“An SAE 5W oil will perform better at low temperatures than a 10W or 15W,” Granger explained. “The five means it thickens at a lower rate in cold temperatures compared to a 10W or 15W. When an oil becomes thick in cold temperatures, it creates drag, so using a 5W-40 oil in cold climates is a good strategy, as the engine will start better in those colder temperatures.”
While some get hung up on the number on the left, Granger said the number people should really pay attention to is the one on the right.
“That’s the number that indicates the viscosity recommended by the OEM for the engine at normal operating temperatures, and is the real indicator of how well an oil will lubricate,” he said.
But, before you default to choosing an oil with a high number on the right, Leonard Badal Jr., Global Delo brand manager for Chevron, said lower viscosity oils can be the right choice for some vehicles.
“Higher viscosity oils are not necessarily always the best oils to select,” he said. “Lower viscosity oils can also provide excellent protection and performance especially for model-years 2012 or newer.”
Differing Oil-Change Intervals
Oil-drain intervals have been widely contended, with extended intervals growing in popularity. But, as we know, contaminated oil affects performance, so what’s the sweet spot?
If you’re looking for the straightforward answer, Middleton offered this for work trucks starting at Class 1-2: “Sticking to the 3,000-mile interval provides a blanket coverage. Following your manufacturer recommendations will also ensure proper maintenance,” he advised.
The 3,000-mile rule is a safe one to follow. But, if you’re looking to truly maximize oil use, a number of other factors can be taken into consideration.
“Work trucks operate in all different manners based on the industry, equipment, environment, and application, and that means determining drain intervals really depends on the truck and how and where it’s being used,” Granger said. “For over-the-road trucks, it’s easier to determine, but work trucks may not get the high mileage OTR trucks see, and so it’s harder to predict. When that’s the case, we suggest identifying the worst-case scenario and basing drain intervals on that. Also, look at the oil-drain interval recommended by the OEM.”
Middleton agreed that the way a truck is being used can affect drain intervals; he suggests reviewing manufacturer classifications for “severe” and “normal” use, then following those guidelines to determine the best interval for changing the oil.
“Most work trucks would fall under the ‘severe’ classification, so the most important factor would be miles operated, followed by time,” he said. “As long as the interval aligns with the way the truck is being used (severe or normal) as outlined by the manufacturer, then that is fine. Extending past the recommended interval can cause premature wear. Although there may be potential cost savings in the short term, in the long-term you could see premature wear on the engine and possible failure with oil related components like lifters, the oil pump, gaskets, and seals.”
Granger said three key indicators can help determine drain intervals: fuel consumption, engine hours, and mileage.
“If possible, it’s best to base oil change intervals on fuel consumption, since that’s the whole reason oil is changed in the first place: the buildup of combustion products in fuel that contaminate the oil and the amount of oxidation which causes oil breakdown,” he said. “The more fuel consumed, the more contaminants build up and eventually require an oil change.”
Badal agreed that fuel burn (or fuel economy) is a good indicator. “Higher fuel burn (lower mpg) means oil changes should be done more frequently,” he said, “whereas better mpg (lower fuel burn) allows the potential to extend oil-drain intervals.”
However, the downside of this method is that it can be difficult to track.
If that’s the case, Granger suggested looking at engine hours.
“In some cases, engine hours are a better indicator as to when oil needs to be changed, especially since vehicles can be operated in different ways,” he said. “For instance, a landscaping truck with a dump body may run without accumulating many miles. But, if it’s idling at a job, it’s still working even though it’s not being driven. In this case, engine hours would be a better indicator.”
However, if a vehicle is strictly over-the-road, Granger said the traditional method of mileage is a reliable guide. “When in doubt, OEM recommendations are a good guide for determining drain intervals,” he said.
Badal summarized it this way: “If the vehicle is located in urban environments and does a lot of stop-and-go work or has a lot of idle time, then hours would be a better option to monitor oil-drain interval changes,” he explained. “If the vehicle operates in rural or in more over-the-road applications, then mileage would be a better way to measure for oil-drain interval changes.”
Beyond factors such as engine type, vehicle use, on-road vs. off-road, type of driving, amount of idle time, payload, geography, weather, and climate, Killips said the oil filter also plays a key role in determining the right drain intervals.
“The fact is, your oil can last longer than you think — but only if you have the right filter,” he said.
In addition to taking the filter into consideration, Killips recommends oil analysis to get the truest feel for when oil should be changed.
“Once fleet managers understand that the oil and oil filter work in unison, they need to have an overall game plan for oil management that is guided by oil analysis. Oil analysis is the best way to determine when the oil should be changed,” he said. “Don’t leave oil-change intervals to chance. There is too much money at stake and too much money to be saved to not have a specific game plan that is designed for a fleet’s vehicle type and usage.”
Badal agreed. “When extending oil-drain intervals, always utilize a used-oil analysis program to confirm oil performance and engine protection,” he said. “Extending oil-drain intervals can help save money by lowering total lubricant, labor and filter costs, along with allowing higher availability of the work vehicles. But, if the program is not managed well, there is the potential to have more engine or reliability issues and lower uptime of the vehicle.”
What About Re-Refined Oil?
Opinions vary on using re-refined oil. Some say it doesn’t offer sufficient purity, while others feel the technology has improved to make it a viable choice.
Middleton sees re-refined oil as being on par with standard oil.
“Re-refined oil is a great product that can help reduce our use of natural resources while still providing a product equal to a standard oil as long as the process is using the newest technology,” he said. “The re-refining process has improved greatly over the past few years and can now provide the exact same benefits and performance as standard oil. Although re-refined oil can sometimes have a slightly higher cost to produce, it helps save natural resources, helps dispose of used oil in a safe way, and promotes a positive image for a company that uses it.”
For Badal, it comes down to the manufacturer.
“The biggest issue with re-refined oils tends to be quality consistency across various suppliers who make these types of products,” he said. “If formulated well from a quality supplier, these products can work fine.”
Do Oil Filters Matter?
As to whether oil filters truly make a difference, the answer in one word is yes. Although not a fluid itself, the oil filter can have a serious impact on the purity of a truck’s oil. But, Killips of HUBB said oil filters haven’t kept pace with developments in engine design and motor oil. While engines and oils have gotten better, conventional filters have, for the most part, stayed the same.
“We believe the oil filter is the weak link in the lubrication system and that conventional filters are limiting the ability of fleet managers to optimize oil-drain intervals,” Killips said. “In some cases, the oil filter becomes full of contaminants, while the motor oil would normally still have useful life. In such instances, contaminants are no longer being removed and the vehicle owner will have to change the oil to prevent the vehicle from running on ‘dirty oil’ and damaging engine components. Had the filter performed up to the level of the oil the oil would have lasted longer. For fleets this could be a huge cost savings.”
When evaluating an oil filter, Middleton said they are graded on three features of functionality:
- Efficiency — the filter’s ability to trap contaminants.
- Capacity — the amount of contaminants a filter can hold.
- Restriction — how much oil is allowed to flow through the filter to provide oil pressure.
“Advancements in oil filter technology have helped to improve all three categories,” Middleton said. “Many of these advancements have been made by removing heavier metal components and replacing them with composite plastics. More manufacturers are also moving to canister-type oil filters versus standard, spin-on oil filters. With these types of oil filters, instead of screwing a standard external oil filter on, a cap is removed and the oil filter is placed inside an internal chamber.”
Middleton said the upside of using canister-type filters is lower cost and increased oil flow; however, it’s important to pay close attention when installing them.
“These filters use O-rings versus standard gaskets and these O-rings must be aligned properly when installed or they can cause an oil leak, lack of oil pressure, and possible engine failure,” he said.
Another alternative to traditional filters, according to Killips, is using computer-designed, surgical stainless steel as the filtering media instead of traditional paper or cellulose fabrics. The filters are washable and are designed to last the life of the vehicle.
Confused about which type of filter to buy? Granger offered this advice: “When in doubt, always use the OEM-recommended filter. If considering an aftermarket filter, be sure to do your research and make sure it meets the requirements the OEM stipulates for the filter. Shell Rotella now has a line of oil filters designed to fit almost every diesel pickup truck on the road today.”