Five to seven engine losses in a year gave the City of The Colony, Texas, a costly maintenance problem, and servicing vehicles more quickly was not correcting it.

During a 2026 Government Fleet Expo & Conference panel, Dustin Palmer, fleet manager for the city, said the turning point came when oil analysis gave the fleet a clearer view of what was happening inside its engines. Palmer explained how those findings changed the city's approach to lubrication and preventive maintenance.

Palmer said the reports showed severe oil degradation, with some indicating that only 5% to 10% of the lubricant’s viscosity life remained after a 3,000-mile service interval. That finding suggested the existing maintenance schedule was not enough to protect the affected engines.

"No matter how fast I could service the vehicles, it wasn't stopping my problem," Palmer told moderator Dan Simpson, product marketing manager at Fleetio.

The city responded by investing more in its lubricants and making oil sample analysis a routine part of its maintenance process. Palmer said the fleet also moved to an oil with a viscosity and grade better suited to the engines showing problems.

Over the following two years, the city lost two engines, compared with the five to seven it had been losing annually. Palmer attributed the decline to the change in lubrication practices and the fleet's use of oil-analysis results.

"Lubrication was a key for us," he said.

Testing at Every PM Service

The Colony now collects oil samples during every preventive maintenance service. Testing is not limited to vehicle engines, as the fleet also collects samples from transmissions, transfer cases, differentials, and blower cases. 

Palmer said the reports can reveal fuel dilution in a diesel engine or identify declining viscosity before a component fails. They can also show metals such as copper, aluminum, or iron. Those findings may indicate internal wear and prompt a closer inspection.

The fleet uploads each analysis report to the asset's documents in Fleetio, which gives technicians access to earlier results when the vehicle returns for service. If a previous sample showed elevated silicon or copper, for example, the technician can look for signs of contamination or bearing wear before submitting the next sample.

Keeping the reports with the asset record also lets the fleet track results over a period of time. Palmer said a concerning reading does not always produce an immediate replacement decision. The team considers whether the condition changes in subsequent samples and whether the result could be related to break-in oil or break-in procedure.

That history helps the city decide whether preventive maintenance can address the condition before it reaches what Palmer described as a point of no return. It can also support a decision to dispose of an asset when the results suggest continued operation carries too much risk.

PM Intervals Follow the Results

The city’s approach doesn't rely on one service interval for every asset; instead, it uses oil-analysis results to determine when each vehicle needs preventive maintenance. Palmer reviews each report and adjusts that vehicle’s PM schedule according to what the sample shows.

"We’ll set the new schedule for the vehicle based on its individual sheet versus a blanket," Palmer said.

If a sample taken during an annual PM service indicates that about 20% of the lubricant’s viscosity life remains, the fleet may shorten the interval. Palmer said a standard 4,000-mile interval works for much of the fleet, but he may reduce an individual vehicle's interval to 2,500 miles when its condition warrants closer attention.

Diesel engines require another level of review because fuel dilution can increase the oil level even when the lubricant continues to maintain its viscosity.

If a sample shows some dilution, Palmer may shorten the next interval by 500 miles and review the next result. The intent is to determine whether the change controls the condition without taking the engine apart or removing the vehicle from service for a larger repair. 

Mileage alone does not tell the full story for many public fleet assets because vehicles can spend hours operating at a work site without traveling a significant distance. A vacuum truck, for example, may run for hours at a water-main break without accumulating many miles, causing an odometer-based schedule to understate how much the engine has operated.

Palmer reviews the period between samples along with engine-hour and odometer readings. Fuel consumption provides another indication of use when an asset has accumulated relatively few miles. He said this combined information helps the fleet judge whether a mileage interval should be shortened to account for operating hours.

The city tracks those operating measures between samples and uses automated notifications to alert supervisors and lead technicians when a unit is due for service. Although the underlying analysis may include several measures of use, Palmer said adjusting the mileage interval can make the service flag easier for employees to follow.

Using Results to Guide Asset Decisions

Oil analysis has also become part of the city’s replacement process by helping Palmer assess whether an asset should remain in service, receive additional monitoring, or be removed before a failure occurs.

The decision begins with relatively small indicators in the sample that can reveal whether a developing issue warrants closer attention. A rise in wear metals may justify another oil change and follow-up test, while a continuing pattern can point to an internal problem that changes the financial case for keeping the asset.

Palmer said the fleet has lost few assets in recent years and that the engines it did lose were covered under warranty. Although the city spends more on oil and testing, he said the reduction in engine losses has helped justify that expense. 

"People leave me alone over the expenditure of our oil because that’s not cheap," Palmer said. "But in doing so, we have saved a lot of assets. I firmly believe it with all my heart."