5 Preventive Maintenance Checks You Should Never Skip

In the fast-paced world of commercial trucking, every minute your rig is off the road is a minute you're not making money. But too many fleet owners and operators still treat maintenance like an afterthought—waiting until something breaks before they act. That reactive mindset can cost you big time in repairs, lost loads, and compliance headaches. Instead, a solid preventive maintenance routine helps you dodge disasters before they start. Let’s break down five critical checks you should never, ever skip if uptime and safety are your top priorities.

Fluid Levels and Condition

Checking your fluids might sound basic, but it's the foundation of preventive maintenance for a reason. Your truck depends on a variety of fluids—engine oil, coolant, transmission fluid, brake fluid, and power steering fluid—to operate safely and efficiently. Ignoring them is like skipping breakfast and expecting to sprint a marathon.

Each fluid has a job to do. Oil keeps internal engine parts lubricated and cool. Coolant regulates temperature. Transmission and differential fluids reduce friction in high-pressure areas. If levels drop too low or the fluid degrades, you’re staring down serious damage, from blown head gaskets to seized transmissions.

Make these steps routine:

• Check engine oil weekly and before every long haul.
• Inspect coolant for level and clarity—milky or rusty coolant means trouble.
• Smell transmission fluid—if it’s burnt, it needs changing.
• Look for leaks under the cab and trailer after parking.
• Top off windshield washer fluid to keep visibility high in tough conditions.

Tire Inspection and Inflation

Tires take more punishment than any other component on a truck. They carry massive loads over long distances, through potholes, under variable weather, and across rough terrain. That means your tire maintenance game needs to be on point. Neglecting it could lead to roadside blowouts, compliance violations, or unnecessary wear on other parts of your rig, like the suspension.

Uneven tread wear is a major red flag that something's off—maybe alignment, maybe shocks, maybe a tire running low for too long. And let’s not forget underinflation, which increases rolling resistance, eats into your fuel economy, and builds heat that can blow a sidewall wide open.

Best practices for tire checks:

• Measure tire pressure on all tires, including the inside duals, weekly.
• Visually inspect for sidewall cracks, cuts, or bulges.
• Use a tread depth gauge—replace tires before reaching minimum legal limits.
• Check for uneven wear patterns and rotate tires on schedule.
• Ensure valve stems are tight and not leaking.

Brake System Evaluation

If there’s one system you absolutely cannot afford to have fail, it’s your brakes. For heavy-duty trucks, stopping power is everything. A well-maintained air brake system not only prevents collisions but keeps you compliant with DOT standards and BIT inspection requirements.

Over time, heat, moisture, and constant use wear down brake shoes, warp drums, and create air leaks in the system. These may not seem critical right away, but they degrade performance steadily until the moment you need to slam the brakes and they’re just not there.

Critical brake components to inspect:

• Air compressor operation and air dryer function (moisture is a brake system killer).
• Slack adjuster stroke—too much play is a red flag.
• Brake drum and shoe thickness—check regularly, not just during PMs.
• Air lines and fittings for leaks or chafing.
• Listen for hissing noises after parking—could be air escaping.

Battery and Electrical System Check

Your truck’s electrical system powers everything from the starter and ECM to lights, sensors, and auxiliary accessories. A weak battery or corroded connection can leave you stranded, especially on cold starts or long hauls. Worse yet, faulty electrical systems can cause frustrating intermittent problems that are hard to diagnose and disrupt your day at the worst possible moment.

Corrosion is the #1 enemy here, especially around terminals. Add in extreme Louisiana heat or moisture from those Prairieville thunderstorms, and you’ve got a recipe for rapid deterioration. Regular inspection and load testing are key to spotting issues early.

Battery system maintenance checklist:

• Clean terminals and check for corrosion every 30 days.
• Ensure cables are tight and secure with no exposed wiring.
• Load-test the battery to confirm proper charge retention.
• Verify alternator output and belt tension.
• Test all lights and fuses regularly.

Suspension and Steering Components

Your suspension and steering systems are crucial not only for ride comfort, but for vehicle control and tire longevity. Worn-out bushings, ball joints, or shock absorbers can make your truck feel floaty, twitchy, or hard to handle—especially at highway speeds or during turns. And these components often degrade slowly, so drivers may not notice until a breakdown or inspection failure.

Since many suspension components bear heavy weight and road abuse, they’re highly prone to wear and metal fatigue. Catching these issues early can save you thousands on replacement tires or axle work.

Don’t skip these suspension checkpoints:

• Inspect leaf springs or air bags for cracks, leaks, or deformation.
  Check for oil leaks on shocks—if it’s wet, it’s done.
• Wiggle components manually to detect worn tie rods or kingpins.
• Look for unusual ride height, leaning, or squeaking over bumps.
• Ensure alignment is maintained to reduce drag and tire wear.

Keep Your Fleet Running with Proactive Checks

Preventive maintenance is about safety, compliance, and operational continuity. Skipping these five checks—fluid condition, tires, brakes, electrical, and suspension—can set off a chain reaction of problems that knock your fleet out of action when you least expect it. At LA Mobile Mechanics LLC, we believe that what you don’t check today could cost you dearly tomorrow.

So get ahead of breakdowns. Make these checks part of your standard routine, and you’ll save time, money, and maybe even lives down the road.

‍