The Role of Adequate Fluid Levels in Maintaining a Healthy Fleet

Usually, you can spot vehicle breakdowns in commercial fleets before they happen. They usually start from something minor. One of the biggest factors? Low and/or dirty fluids.

Ignore checking oil, coolant, brake fluid, and transmission fluid, and you'll surely be in for car trouble. And unless you’ve got one truck, if you’re managing multiple trucks, those “minor” problems can add up quickly.

At Kooner Fleet Management Solutions, we’ve seen it all — engines that have seized because a driver didn’t check for low oil or brakes that failed because someone didn’t stop to check the fluid level. So now the time has come for us to talk about fluids you tend to regularly, that allow your trucks to get out and to stay out on the road, and how to manage them like a professional.

Why You Should Not Skip Routine Fluid Inspections

Every vehicle has fluids that need to be managed for the vehicle to perform properly. Fluids regulate the temperature, reduce friction, transfer power, and decrease corrosion.

If just one of these systems runs out or is contaminated, it puts the entire truck- and all your scheduling- at risk. Fleet Maintenance Magazine noted that more than 60% of engine failures may have been avoided if the driver had performed a fluid inspection in their normal routine maintenance. This is not just a statistic, this is avoidable downtime.

Key Fluids You Should Regularly Attend To

The following needs your regular attention:

Engine Oil

Think of oil as the lifeblood of your engine. Oil allows the engine's moving parts to move under a thin film of protection to keep the parts from wearing out. When the oil is low or due to a breakdown in properties, friction occurs, and friction increases heat and the parts wear on each other - literally.

✅ Oil level: Every 8,000–10,000 km or before extended trips

✅ Red flags: Dark oil or thick oil, strange noise from the engine, or oil light on

Add on a smart Last mile Maintenance Service, and you'll never worry about it getting missed again.

Coolant (anti-freeze)

The coolant controls the temperature of the engine. If the coolant is too low, you run the risk of the vehicle overheating. If contaminated, the coolant cannot perform its job.

✅ Check frequency: Visual check weekly, full flush every 2 years

✅ Red flags: Engine is overheating, puddles under the radiator, rusty colored fluid

Brake fluid

This is non-negotiable. Stopping power in your fleet depends on proper brake fluid levels. If the brake fluid is too low or contaminated, the brakes don't work properly or efficiently, particularly when carrying a load or weight.

✅ Check frequency: Every 6 months

✅ Red flags: Spongy brakes, brakes do not stop quickly, brake light comes on

Transmission fluid

This is especially important for autonomous vehicles. Transmission fluid keeps everything from overheating and changing gears smoothly.

✅ Check frequency: every 50,000–80,000 km

✅ Red flags: Transmission slipping when going in gears or running fine, no response when you push the accelerator, the color of the fluid is unusual.

Power steering fluid

The operation of larger vehicles, such as trucks or trailers, is tremendously easier because it rejuvenates the operation of the steering.

✅ Check frequency: monthly

✅ Red flags: The steering wheel is stiff when turning, whining noise when turning the steering wheel.

Windshield Washer Fluid

A dirty windshield can reduce visibility and cause an accident. It's important to use your windshield wipers to keep your windshield clean.

✅ Check frequency: weekly

✅ Red flags: Reservoir low, still hard to see or keep clarity even after using wipers.

Fluid Health = Fleet Health

When fluid is low or dirty, every component of your truck has to work harder than it needs to. That translates to:

Decreased fuel efficiency
Increased wear and tear
Increased operating temperatures
Increased risk of roadside breakdowns

Fleet vehicles that maintain regular fluid service, according to Geotab fleet insights, see 18% fewer unscheduled service stops. That's significant when you're budgeting for uptime and ROI.

Set It and Forget It? Not Exactly

It's easy to depend on dashboard notifications or simply trust drivers to raise the red flag, but with the numbers and speed most fleets operate at, that's not a good idea. Instead:

Create a preventive maintenance program based on fluid inspections
Digitize your logs through fleet apps or dashboards
Have a team do the routine maintenance (our fleet maintenance and repair capabilities can do just that)
Teach drivers with basic pre-trip checklists
Apply telematics to track engine temperatures and fluid conditions

How Kooner Fleet Management Solutions Helps

We make fluid checks part of your routine, not a crisis response.

Here’s how we support you:

Scheduled on-site inspections
Real-time monitoring with sensors
24/7 roadside assistance service if something goes wrong mid-route
Truck and trailer repair with genuine parts
Custom maintenance dashboards to track everything from oil change intervals to coolant cycles

Whether you're running cross-country hauls or last-mile delivery routes, our goal is to catch the small stuff before it becomes a problem.

Final Thoughts

Proper fluid levels may seem like a minor detail, but they’re a cornerstone of long-term fleet health. Trucks that run with clean, full fluids last longer, perform better, and cost you less — period.

If you’re chasing reliability, better mileage, and fewer emergency repairs, start with the basics: check your fluids.