How to Buy a Used Semi Truck A to Z

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Welcome to this in-depth guide on purchasing a used semi truck, built on my 16 years of experience in the trucking industry—from building trucks at the factory to handling dealership sales and financing, and accounting. This is one of the most detailed resources I’ve ever put together, and you can read the sections that matter most to you or dive into the whole thing to apply my insights. This guide is a work in progress, so if there’s a topic you want me to cover, let me know, and I’ll consider adding it. I’m focusing on used trucks, as they come with more risks than new ones, and I’ll walk you through the key steps to make a smart purchase. Whether you’re an owner-operator, managing a large fleet, or dispatching trucks, your business model shapes your truck choice, and this guide will help you navigate the process.

Current Market Overview (July 2025)

As of July 2025, the used truck market has shifted to a buyer’s market, with improving inventories giving buyers more leverage than in recent years. Prices are still elevated from pre-2021 levels, when used truck costs nearly doubled, but they’re softening compared to the 2021-2022 peak. You can find better deals on higher-mileage trucks (300,000–500,000 miles), but thorough inspections remain critical to avoid costly repairs. With more trucks available, now’s a good time to shop smart and negotiate.

Choosing the Right Truck

Every trucking business is unique, and your model drives your truck choice. Some of you want to be owner-operators with one reliable rig, while others manage fleets of hundreds or focus on dispatching. Some run small fleets of older less expensive trucks, keeping one in the shop for rebuilding as part of the plan, while others prefer newer models for reliability. In today’s market, new trucks are often scarce or overpriced, making used trucks a practical choice if vetted carefully. My approach to buying is methodical: Figure out exactly what you want—specific features, engine, transmission—research online, verify availability, and show up at the dealer ready to negotiate. For example, contact a dealership to confirm they have the truck you’re looking for before hitting the lot. This ensures they have what you need, even if it means traveling a bit. Most people browse lots and pick from what’s available, which can work but risks settling for less. I’ve seen folks buy trucks they didn’t plan on because they got swayed on the lot—sometimes that can be a good thing. If you’re in the business of driving, don’t be afraid to travel for the right truck. Know your must-haves upfront to avoid wasting time or money.

Major Truck Components

The engine and transmission are the heart of an over-the-road (OTR) Class 8 truck, and your choices here are critical. From my experience building and selling Freightliners, I recommend Detroit Diesel or Cummins engines for their reliability and performance. If I had to pick a third, it’d be a Volvo engine. Paccar engines, found in Kenworth and Peterbilt trucks, get mixed reviews—some operators love them and keep buying, while others avoid them. International trucks with Cummins engines are solid, but their MaxForce engines have struggled to regain trust in the OTR market after past issues. Your engine choice depends on your application—OTR, heavy haul, dump trucks, or oil field work—so research what fits. I focus on OTR trucks, as vocational trucks aren’t my specialty. On transmissions, most OTR drivers prefer automatics, and the Detroit Diesel DT12, exclusive to Freightliner with a Detroit engine, is my top pick for its durability and minimal issues. Volvo’s iShift is a strong second, while Eaton’s new 12-speed automatic is promising but may have early issues—ask around before deciding. Emissions systems, mandated since 2007, add complexity with DEF fluid and DPF filters. Early systems were problematic and expensive, but manufacturers have improved reliability. To avoid costly repairs, keep DPF filters clean—check ash levels at service shops and act before they hit 80%. Excessive idling clogs filters, so avoid it. New or remanufactured DPF filters, needed roughly every 400,000 miles, are better than cleaning, which might last a year or 100,000 miles if you’re lucky. Avoid cheap emissions deletes—they can destroy your truck and prevent service at authorized dealers. If you go this route, use the best, not the cheapest.

Warranty Considerations

Warranties can save you from unexpected repair costs, so think about them before buying. Most used trucks leave the lot with minor issues costing $1,000–$2,000, depending on the dealer’s prep work. Most big dealers do more to their trucks and have deeper pockets for post-sale support, but don’t assume they’ll cover everything. If you find a truck with an existing factory warranty, ask if you can extend it—if it’s available it’s a great deal. There’s no “bumper-to-bumper” warranty for trucks, but you can get coverage for major components like the engine, transmission, and rear axles. A 1-year/100,000-mile warranty for internally lubricated parts might cost $3,000 and cover catastrophic failures like a blown engine, which is rare but devastating on a 400,000-mile truck. I’ve seen a warranty save a buyer when an engine failed at 380,000 miles. Higher-tier warranties cover turbos and injectors, which make up 80% of claims, per warranty companies. First-time buyers with tight budgets should consider a warranty, which can be financed, giving you time to save for repairs. Some dealers offer limited post-sale support, like covering repairs up to $500, but most sell as-is. I’ve seen dealers cover repairs up to $12,000 after a sale, but don’t expect them to fix minor stuff like a cigarette lighter—save your leverage for bigger issues. If a major problem hits right after purchase, contact the dealer, get a service shop to assess it, and present the bill to see if they’ll cover or split the cost.

Financing Your Truck

Financing a truck is like buying a car—you need to know what you can afford before hitting the dealership. Brokers can help clients get pre-approved, so they know their monthly payment, down payment, and loan amount upfront. A broker gives you buying power nationwide, unlike dealership approvals that often lock you into one lot. Big dealers have high overhead—fancy buildings, managers, sometimes stockholders—which can mean less attractive financing terms. Brokers can keep costs low, passing savings on to you. With the high price of semi trucks you might consider GAP insurance if you’re financing, to avoid a big bill if your truck is totaled or stolen. Lenders look at three things: your down payment (typically 20% for a $100,000 truck), at least two years of driving experience, and a 600+ credit score with no current delinquencies like back child support or recent bankruptcies. Good credit might get you 10% down or, rarely, zero down. First-time buyers with less experience or no credit may need 40% down and face 10–20% interest rates. Experienced buyers with commercial credit can often get rates below 10%.

Inspecting the Truck

Inspecting a used truck is critical, as most come from large fleets without maintenance records. Big dealers should provide records of their work or warranty repairs. Start with a safety check: Are tires flat? Is there fuel? Is the windshield cracked? Look for accident signs—mismatched paint, uneven hood closure, or different headlights could mean minor repairs, but a replaced frame rail is a huge red flag. Ask for a RIGDIG report, like a Carfax for trucks, to spot major accident history. Start the engine and listen for knocking, rough idling, or squealing belts, and check for oil leaks with a flashlight, even under the truck. Test all lights, brakes, windows, mirrors, and the APU if equipped. For heavy haul or reefer, ensure the truck’s setup (horsepower, gear ratio, sliding 5th wheel) fits your needs. On a test drive, check if the truck drives straight, the steering wheel is aligned, and the transmission shifts smoothly in all gears. Look for dash warning lights, test the engine brake, cruise control, and A/C, and ensure no water leaks in the cab. Some dealers offer dyno tests for $400 to check engine performance, but most buyers (myself included) find them hard to read, so weigh the cost. I’ve seen buyers range from those who walk around a truck once and buy it to those who inspect like mechanics. Hiring a mechanic for $300 can help if you’re unsure, but ensure they know trucks.

Negotiating the Deal  (This is IMPROTANT!)

Negotiating depends on the market, and in July 2025, it’s a buyer’s market with more trucks available, giving you room to push for deals. Start with mechanical repairs over price cuts, as repairs can balloon—a $300 alignment might reveal $2,000 in king pin issues, or a squealing belt could mean a $4,000 A/C compressor fix. Dealers are more likely to fix mechanical issues before the sale than after, when trucks are sold as-is. If you spot problems like faulty lights or DPF filter issues, ask the dealer to address them first. Once repairs are settled, consider asking for a warranty ($3,000–$5,000 range) instead of a price cut, as it’s easier for dealers to include and protects you from future costs. Warranties cost dealers less than their face value, so a $3,000 warranty might cost them $2,000, making it a better ask than a straight discount. If you want a price reduction, aim for $5,000, and in a buyer’s market, you might get it. Alternatively, a down payment match keeps cash in your pocket, like a price cut but reducing your upfront cost. Work with your salesperson to find a number that’s tough for the dealer but not so high they let you walk. Show you’re serious with a financing pre-approval, and avoid lowball offers that get dismissed. Build rapport, inspect thoroughly, and negotiate repairs before price to maximize value. If a major issue hits post-purchase, contact the dealer immediately, get a repair estimate, and see if they’ll cover or split the cost—stay professional to get results.

Final Thoughts

Buying a used semi truck is a big investment, but with preparation—knowing your needs, inspecting thoroughly, and negotiating smartly—you can secure a reliable rig that fits your business. My 17 years in trucking, from factory floors to financing deals, have taught me how to avoid pitfalls and find value. Whether you’re a first-time buyer or a seasoned fleet operator, I hope this guide helps you make a smart purchase.
 
 
How to Buy a Used Semi Truck A to Z
                                                           
CHECKLIST
 

ON THE LOT INSPECTION:

• Rigdig report
• Service and warranty records
• Engine model, horsepower, torque
• Rear axle(s) gear ratio
• Verify miles and VIN (take pictures)
• Any dash lights or check engine type of lights on
• PM completed
• No shiny objects on dipstick oil when checking engine oil
• Coolant at proper level
• DPF ash level
• Oil or coolant leaks
• Engine sound (idle, knocks, squealing)
• Exhaust smoke
• Brake pads
• All lights
• Mirrors, windows, windshield, sunroof
• Silicone around windshield gasket (possible leak)
• Windshield wipers
• Air leaks
• Keys work in all doors and ignition
• Hood closes properly
• Paint (aftermarket or factory)
• Rust
• Tires
• Sliding 5th wheel
• APU functioning
• AC functioning
• Fire extinguisher and triangle reflectors
• Cabinets functioning
• Mattresses
• Seats working
• All dash switches working

 
 
TEST DRIVE:

• Steering wheel straight
• Does it drive straight
• Is it hopping
• Transmission working in every gear including reverse
• Power is good
• Clutch
• Braking in a straight line
• Engine brake functioning
• Cruise control functioning
• Any speed parameters on pedal or cruise
• Any out of the ordinary noises
• If raining is there water on the inside of windshield

Thank you and drive safe,

DISCLAIMER
The information provided in this report does not and is not intended to, constitute legal or any other advise, instead, all information, content, and materials available on this report are the writers opinion only and for general informational purposes only. Information in this report may not constitute the most up to date legal or any other information.