The more your trucks stay on the road and out of the shop, the better for your bottom line. Which begs the question: How long can your trucks go before they need an oil change?  

The number of miles or amount of time between a vehicle’s oil changes is known as the oil drain interval (ODI). Optimizing ODI is a worthy pursuit, because it’s better for your trucks as well as your budget.

Fleets want to get the most out of their investments, and that includes consumables like motor oil. If you can extend your ODI, the potential benefits include reducing your expenses, decreasing downtime, maximizing the value of your oil, and cutting waste. In the right conditions, some trucks can travel as far as 60,000 miles before they need an oil change.

On the other hand, taking ODI too far — keeping oil in the truck too long before draining and replacing it — runs the risk of diminishing performance, damaging the vehicle, and possibly voiding the engine warranty.

So how do you get the most out of your oil without going too far? Here are four key factors to help you find the right balance.

1. OEM Guidelines

The demands placed on engine oil vary from vehicle to vehicle and engine to engine. For that reason, the top tool in finding the ideal ODI for a specific truck and engine is the original equipment manufacturer’s (OEM’s) guidance.

“The first thing to consider is the OEM recommended drain interval for the duty cycle of the fleet to ensure meeting warranty specifications,” says Cornelius Jones, fleet technical expert at Shell.

Keeping oil in the engine too long can void the warranty. Moreover, as the oil’s lubricating properties decrease and contaminants build up, wear on the engine increases and protection decreases. This can lead to bigger maintenance issues and costs down the road.

Check the truck’s manual or consult the OEM to find the recommended ODI. Jones notes that the manufacturer’s recommendation may vary based on operating factors (gross volume weight, fuel economy, idle time, load factor, etc.), which are also important in the ODI equation.

2. Operating Conditions

The ideal ODI for your truck will depend on a number of operating factors. Essentially, the more severe the duty cycle and service environment, the sooner the oil will need to be replaced.

For example, when a vehicle operates in a hot and dusty environment, the engine oil is subjected to added stress and particulates, both of which decrease its effectiveness. Similarly, heavy loads mean higher engine temperatures, which can shorten the time between oil changes.

Another factor that plays into ODI recommendations is fuel consumption. In severe service, the engine uses more fuel to generate more power. This is a less fuel-efficient condition, and the oil deteriorates faster because it has to deal with more contaminants, oxidation, and acidic compounds. All of which explains why fuel consumption affects ODI. 

“Many manufacturers will recommend oil drain intervals based on the fuel consumption of your engine,” Jones says. “If the truck has lower fuel consumption — increased fuel efficiency, normally greater than 6 mpg — you will be able to extend the drain interval further than it would be in a more severe operation.”

Idle time can also influence ODI. If your truck idles for long periods or a high percentage (more than 30 minutes or more than 20% of operating time), the oil may need to be drained sooner. For a more accurate assessment, Jones suggests that fleets with high idle periods consider an ODI based on hours instead of miles.

3. Engine Oil Specification

To further optimize ODI, fleet operators should consider using a premium oil that meets a higher specification. In some cases, this can enable trucks to travel thousands of miles more between oil changes compared to lower-specification oils.

The American Petroleum Institute (API) has two current diesel engine oil standards/categories: CK-4 and FA-4. Jones explains that both of these standards provide multiple benefits beyond earlier oil standards.

CK-4 oils offer improvements over the previous CJ-4 standard with enhanced protection against oil oxidation and engine wear, particulate filter blocking, piston deposits, and degradation of low- and high-temperature properties.

FA-4 oils provide all the benefits of the CK-4 formulations, but they are formulated with a lower HTHS (high temperature high shear) viscosity, which can boost fuel economy compared to oils with higher HTHS viscosities.

Jones notes that while the CK-4 standard is backwards-compatible with the older CJ-4, OEMs have only approved FA-4 for 2017 vehicles or newer.

So how do these newer standards impact oil drain intervals? In short, they can pave the way for longer extensions of ODI, empowering fleet operators to reduce their oil consumption and costs.

For example, a long-haul truck with a Detroit DD15 engine using the older CJ-4 spec oil will require an ODI of 50,000 miles. By contrast, the same truck and engine using the current CK-4 spec oil can go up to 60,000 miles before it needs an oil change, depending on the operating factors. That’s a 20% increase in ODI.

As a caveat, fleet operators should also factor in other preventive maintenance (PM) needs when determining their ODI.

“Since oil drain is not the only service during a PM,” Jones says, “a fleet needs to make sure that the ODI allows other services on gears, wheel ends, chassis, etc. to be performed at the required interval.”

Meanwhile, premium oils can provide benefits beyond extending ODI. For instance, Shell’s Rotella product line boasts improved base oils that boost oxidation control, shear stability, and aeration control — all of which translate into better protection for your engine.

4. Oil Analysis

For further insights on ODI, fleet operators can tap into oil analysis, which detects contamination and other conditions that could cause premature engine wear and unplanned downtime.

Jones explains that in cases like overextended drain intervals or leaks in the air intake system, a lab can detect small abnormalities long before your mechanics can.

“The knowledge gained from a consistent oil analysis program can assist you in optimizing your oil drain interval, help increase equipment reliability, minimize unscheduled downtime, and more precisely track operating efficiency and maintenance practices,” Jones says. “This combination can help lower total operating costs.”

Additional Resources

Shell offers oil analysis with its Shell LubeAnalyst service.

For assistance with ODI optimization and other engine oil topics, fleet operators can consult their Shell Rotella distributor or call the Shell Technical Help Desk at 1-800-BEST-OIL.

Also, Shell’s LubeMatch tool provides ODI information and oil recommendations for specific engines.

For more on Shell’s Rotella diesel engine oil line, go to rotella.shell.com.