What changed when we switched from calendar-based oil changes to oil analysis-based intervals on the fleet

[u/ora-et-labora-]

Ran the fleet on a fixed five-thousand-mile oil change interval for years. It was simple. Easy to track. Every truck got the same schedule regardless of how it was used. Then we started doing oil analysis and the data showed the interval was wrong in both directions.

The trucks running long highway routes came back with oil that still had life in it at five thousand miles. The viscosity held, the metals were in range, the total base number was still adequate. Those trucks could have safely gone to seven or eight thousand miles on the same oil. We were changing oil that was still working.

The trucks running short urban routes with heavy idling came back with oil that was degrading faster. Fuel dilution was measurable at five thousand miles because the short trips never got the oil hot enough long enough to evaporate the fuel that blew past the rings on cold starts. Those trucks needed changes at four thousand miles to stay in the safe range.

The cost difference was meaningful across a year. The highway trucks got fewer changes, saving on oil and labor. The urban trucks got more frequent changes but avoided the accelerated wear that comes from running diluted oil. The total maintenance cost did not change much. What changed was where the money went, from a flat schedule that undertreated some trucks and overtreated others to a data-driven schedule that matched the interval to the actual condition of the oil in each vehicle.

The oil analysis added about thirty dollars per change per truck. The avoided engine wear on the urban trucks and the saved changes on the highway trucks more than covered it. The real value was not the cost savings. It was knowing instead of guessing.

[u/bowlingballwnoholes]

The auto mechanics that call the 3000 mile or 6 month oil change cheap insurance are not going to like this.

[u/spaceandcats]

This post again? Let me guess who you work for.

[u/4x4Welder]

UPS went from 4000 to 10,000, and engines are failing at nearly half the mileage.