Two truck drivers standing in front of trucks

Managing a mixed fleet is like juggling swords and rubber chickens at the same time: some tools require precision, others just need to keep rolling. But if you build a maintenance plan that actually works, you’ll keep downtime low, costs predictable and your fleet reliable. Here’s how.

Why Mixed Fleets Are a Maintenance Challenge

First, let’s face it: mixed fleets (vehicles of different types, brands, duties) complicate things. According to industry research:

Mixed fleets force you to manage multiple maintenance tracks, parts inventories and expertise levels. Read more about mixed fleets here

Maintenance software, telematics and data integration become more critical — because one size does not fit all. Learn more how to build effective maintenance strategy here

Each asset (truck, trailer, van, specialty rig) may have different OEM specs, usage profiles, duty cycles and therefore different maintenance needs.
So your goal is: bring order to chaos. Build a plan that’s robust yet flexible.

Step 1: Inventory and Categorize Your Fleet

Before you schedule anything, know what you’ve got.

Create a detailed inventory: vehicle ID, make/model, year, duty cycle, mileage/hours, trailer or non-power unit, on-road or off-road.

Break your assets into categories (e.g., heavy-duty trucks, light service vans, trailers, specialty equipment). Read more about fleet maintenance calendar for mixed fleet here.

Identify critical assets: Which pieces, if down, cost you most (lost revenue, regulatory risk, customer dissatisfaction)? These deserve higher priority.

Step 2: Define Maintenance Triggers & Intervals

Mixed fleet means you’ll deal with time-based, mileage-based, hour-based, and usage-based triggers.

For trucks: mileage and hours matter.

For trailers or equipment: hours or cycles might be more relevant.

Some tasks could be calendar-based (seasonal checks) regardless of mileage.
For example, HVI guide states: “Different equipment types have varying maintenance intervals… require specialized technicians, parts inventories, and operating conditions.”
Action points:

For each category, define primary trigger (miles/hours/calendar).

Map tasks to those triggers (oil change at 25k miles, air system check every 500 hours, brake inspection every 6 months).

Flag “severe duty” or “harsh environment” assets to shorten intervals when needed.

Step 3: Standardize Maintenance Tasks & Procedures

To keep things manageable across brands/types:

Develop procedure templates for each category: what to check, what parts to inspect/replace, what documentation to capture.

Use checklists (daily, weekly, monthly) to ensure consistency.

Train technicians and drivers accordingly — with mixed fleets the “same old” approach fails because systems differ.

Maintain a parts inventory strategy: different makes/models = different parts, so avoid stockouts and expensive rush orders.

Step 4: Leverage Technology & Data

You can no longer rely on sticky notes and paper logs if you want smooth operation. Tech helps.

Telematics, onboard diagnostics and fleet software help unify data across brands. Kooner FMS article shows how “on-board technologies are transforming mixed fleet maintenance.”

Use a fleet maintenance management system that tracks service history, triggers alerts when tasks are due, logs downtime, and provides analytics.

Use dashboards to spot trends: which asset types cost more, which ones have more breakdowns, where you’re missing scheduled maintenance.

Step 5: Build a Maintenance Calendar & Scheduling Strategy

With categories, triggers, procedures and tech ready, build your calendar.

Use daily/driver pre‐trip checks: Tire pressure, lights, fluid levels. These apply across the board.

Use weekly/monthly tasks: Check belts, hoses, filters, suspension, air systems.

Use quarterly/semi-annual/annual tasks: Major inspections, full fluid flushes, structural checks.

Adjust for seasonal changes: winter prep, summer cooling system focus, etc.

Implement routing/ downtime planning: schedule tasks when the asset is parked, off duty, or during slack time.

Step 6: Monitor KPIs & Continuous Improvement

Every plan needs measurement. Set clear metrics and review regularly. Useful KPIs:

Percentage of scheduled maintenance completed on time

Emergency repair/unscheduled downtime %

Cost per mile/hour by asset type

Mean Time Between Failures (MTBF)

Parts inventory turnover

Technician productivity
Then:

Review results monthly/quarterly.

Adjust intervals, task lists, or procedures based on what the data tells you.

Share feedback with drivers/technicians and refine the process.

Step 7: Communicate & Train Across Your Organization

Maintenance is not just the shop’s job — drivers, supervisors, dispatchers all play a role.

Train drivers on pre-trip checklists and how usage affects maintenance.

Communicate with dispatchers/route planners about downtime windows and maintenance scheduling.

Train technicians in multi-brand diagnostics/troubleshooting for your diverse assets.
Again: with mixed fleets you’ll need broader skillsets.

Step 8: Plan for Parts, Supply Chain & Budget Realities

Mixed fleets bring parts and logistic complexity. You’ll face: different OEMs, longer lead-times for specialty items, and higher parts cost variability.

Build a parts strategy: critical spares on hand for high-priority vehicles, bulk ordering for common components.

Track parts usage by asset type to forecast spend.

Budget for variability: mixed fleets may have more “unknowns” than single-make fleets.

Step 9: Implementation Plan – From Pilot to Fleet-wide

Rolling out this plan in one go is tempting but risky. Better approach:

Pilot phase: Choose one asset category (e.g., heavy trucks) or group of vehicles.
Test triggers, tasks, software, data collection.
Refine: adjust intervals, fix any workflow issues.
Expand: rollout to other categories (vans, trailers, specialty) once initial success is met.
Continuous rollout & feedback loops.

Step 10: Align Maintenance Plan with Business Goals

Finally, your maintenance plan must serve your business. Consider:

Uptime targets: The plan should support meeting delivery/service commitments.

Budget constraints: Preventive maintenance should cost less than reactive downtime.

Compliance & safety: Especially for commercial trucks, trailers and potentially regulated equipment.

Resale value: Good maintenance extends asset life and improves resale or lease return value.

Scalability: As fleet grows or changes (new brands, EVs, specialty equipment), your plan should adapt.
With a solid plan you reduce surprises, control costs and extend your trucks’ lives.

Common Pitfalls to Avoid

How Sounders Truck Repair Can Help

At Sounders Truck Repair, we specialize in maintaining mixed fleets of heavy-duty trucks, trailers, service vans and specialty work rigs. We offer:

Fleet diagnostics across multiple brands/models.

Customized preventive maintenance plans built on your usage, vehicle mix and business goals.

Part inventory sourcing and on-site planning to reduce downtime.

Real-time data analytics and reporting to monitor KPI performance and cost.
If your fleet mix is expanding, or you feel maintenance is reactive instead of proactive — let us show you a better way.

Conclusion

Building a maintenance plan that works for mixed fleets is not simple — but it’s absolutely achievable. You need: clear inventory & categories, tailored triggers/intervals, standardized procedures, technology to support execution, measurement to drive improvement, and alignment with business goals.
Do this well and you’ll shift from firefighting breakdowns to proactive uptime. Your fleet will run smoother. Your costs will stabilize. Your business will move forward — reliably, profitably.

Need help getting started? Contact us at Sounders Truck Repair here — let’s build a plan together that keeps your fleet moving.

How to Build a Maintenance Plan That Works for Mixed Fleets