Fleet maintenance schedule for the vehicles you actually run. A severe-duty schedule from a Denver fleet shop.

Fleet vehicles wear faster than retail vehicles because they work harder. Don's Garage at 5515 Washington Street in north Denver has been keeping work vehicles on the road since 1970, three generations of mechanics. The schedule below is what we recommend across the most common fleet vehicles — cargo vans, pickups, SUVs, and sedans — tuned for severe-duty operation rather than the manufacturer's retail-customer assumptions.

Use it as a baseline. Every fleet's specific duty cycle is different, which is why we build customized schedules for fleet customers based on their actual vehicles, mileage tiers, and operating patterns. The general framework below is the starting point.

Why fleet vehicles need a different schedule.

Ford classifies fleet usage as "severe duty" — and it's not marketing language. Ford's own owner's manuals draw a distinction between normal-duty driving (highway commuting, occasional errands) and severe-duty driving (frequent short trips, heavy loads, dusty environments, towing, extended idling, daily commercial use). Most fleet vehicles check at least three of those severe-duty boxes.

A severe-duty maintenance schedule cuts standard intervals roughly in half. Oil changes go from 7,500-10,000 miles to 5,000-7,500. Transmission services drop from 100,000 miles to 30,000-60,000. Coolant flushes shift from "lifetime" to every 60,000-75,000 miles. The pattern is consistent across manufacturers — Ford, GM, Ram, Mercedes, Toyota all publish severe-duty schedules that are dramatically shorter than the schedules dealers tell retail customers about.

One independent fleet manager profiled in a Work Truck Online case study cut his transmission service interval from the manufacturer's recommended 70,000 miles to 30,000-50,000 miles for his fleet. His result: zero transmission failures in five years. That's the math: a $300-$500 transmission service every 30,000 miles is dramatically cheaper than one $4,000 transmission rebuild plus 5-7 days of downtime.

Service intervals by mileage tier.

Below is the severe-duty schedule we recommend for most fleet vehicles, regardless of make. Vehicle-specific notes follow in the next section.

Every 5,000 miles (or 6 months, whichever comes first).

• Oil and filter change (full synthetic recommended for fleet duty)
• Tire pressure check, including spare
• Tire rotation
• Brake inspection (visual check of pads, rotors, lines)
• Multi-point inspection: lights, wipers, fluid levels, belts, and hoses
• Battery condition check (especially for vehicles with lots of start-stop cycles)
• Air filter inspection (replace if dirty, often by 15,000-30,000 miles depending on environment)

Every 15,000 miles.

• Everything in the 5,000-mile interval
• Cabin air filter replacement
• Fuel filter inspection (replace per manufacturer interval, typically every 30,000-60,000 miles)
• Brake fluid level and condition check

Every 30,000 miles.

• Everything above
• Transmission service for vehicles in heavy duty (towing, hauling, frequent stops). For lighter-duty vehicles, the next service can wait until 50,000-60,000 miles. Either way, do not wait for "lifetime" fluid recommendations — fleet usage breaks fluid down faster than retail driving.
• Differential and transfer case fluid check (replace at 50,000-60,000 if not replaced earlier)
• Spark plug inspection (replace at 60,000-100,000 depending on vehicle and fuel)
• Suspension and steering inspection (ball joints, tie rods, control arms, sway bar links)
• Engine air filter replacement if not done earlier

Every 50,000-60,000 miles.

• Everything above
• Transmission service if not done at 30,000 (for lighter-duty vehicles)
• Differential and transfer case fluid replacement
• Coolant flush (do NOT trust "lifetime coolant" claims for fleet usage)
• Brake fluid flush
• Drive belt and timing belt inspection (timing belt typically replaced at 100,000-120,000 miles if vehicle has a belt rather than a chain)
• Power steering fluid replacement (manufacturers often don't specify an interval — 60,000 miles is a reasonable conservative target)

Every 100,000 miles.

• Everything above
• Spark plug replacement (if not done earlier)
• Timing belt replacement (if equipped — many newer vehicles use chains that don't need replacement)
• Water pump inspection or replacement
• Engine and transmission mount inspection
• Major fluid flush across all systems if any have been deferred

After 150,000-200,000 miles.

• Continue the schedule above on rotation
• Increased frequency of inspections — fleet vehicles past 150,000 miles enter the wear-failure zone where injectors, water pumps, alternators, starters, suspension components, and emissions hardware start failing in sequence
• Annual oil sampling becomes valuable for catching engine wear before catastrophic failure
• Plan for the rotation-out decision: at 250,000-300,000 miles, most fleet vehicles cost more in maintenance and downtime than a replacement vehicle costs to acquire

What fails at what mileage.

Every fleet vehicle hits roughly the same failure curve. Use this to plan budgets and replacement timing.

40,000-60,000 miles.

Brake pads (front first, rears last longer). First set of tires reaching minimum tread. Battery on most vehicles. Wiper blades (multiple times by now). Air and cabin filters multiple times.

60,000-100,000 miles.

First major service inflection point. Brake rotors typically need replacement (resurface or replace). Spark plugs on most vehicles. Coolant flushed (or should be). First transmission service if not done earlier. Front suspension components (control arm bushings, sway bar links) start showing wear. Some vehicles see ignition coil failures.

100,000-150,000 miles.

Water pump becomes a common failure point. Timing belt (if equipped) needs replacement. Front suspension components typically need replacement (ball joints, tie rod ends, control arms). Brake calipers can start sticking. EVAP system components fail. AC system service (refrigerant top-off, condenser inspection) commonly needed. Some transmissions show first signs of slipping or hard shifting.

150,000-200,000 miles.

Wear-zone failures begin. Alternator and starter often need replacement. Fuel pump fails on some vehicles. Major suspension overhaul commonly needed. Transmission may need rebuild if maintenance was deferred. Engine mounts and transmission mounts deteriorate. Catalytic converters on some vehicles. Power steering pump fails on some vehicles.

200,000-300,000 miles.

Decision zone. Vehicles with disciplined maintenance routinely run to 300,000+. Vehicles with deferred maintenance typically don't make it past 200,000-250,000 without a major repair that exceeds the vehicle's value. This is where fleet managers face the rotation decision: invest in a $4,000-$8,000 repair, or rotate the vehicle out of revenue duty into backup or sale.

How Don's helps fleet customers actually use this.

A maintenance schedule is only useful if someone follows it. Most fleet operators we work with don't have time to track service intervals across 10-30 vehicles, and CMMS software is overkill for a fleet that size. Don's offers a simpler alternative.

Bring your fleet by for a baseline assessment. We log each vehicle's current mileage, recent service history (whatever you have), and condition. We can build a forward schedule for each vehicle in your fleet based on its specific mileage tier and duty cycle. We can send reminders when each vehicle is due. You bring it in, we do the service, you don't have to think about it again until the next reminder.

Records are itemized — what was done, what parts, what labor, what mileage. Useful for your own fleet records, useful for resale value when you eventually rotate vehicles out, useful for warranty work down the road.

Single point of contact. The person who books your first truck can keep handling your account whenever possible. Over time, they get to know your fleet, your duty cycles, your preferences. They know which trucks tow, which ones run city routes, which ones idle a lot. The schedule for your fleet ends up being more accurate than what any generic schedule could provide.

Want this schedule built for your fleet?

Bring your fleet to Don's at 5515 Washington Street in Denver. We'll spend an hour with each vehicle, document where each one stands, build a forward schedule, and start tracking it for you. No commitment, no hard sell. The first conversation is just figuring out what you've got and what makes sense.

Call (303) 295-2448