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Semi Trucks & Engines

Compare heavy-duty truck models, engine configurations, ownership costs and decisions about buying or replacing equipment.

Two heavy-duty diesel truck engine compartments shown side by side in a workshop.

Cummins X15 vs. Detroit DD15: Specs, Service and Costs

Compare the Cummins X15 and Detroit DD15 using verified engine specs, maintenance intervals, service access, fuel-cost examples, and a buyer checklist.
Two aerodynamic long-haul semi trucks parked side by side at a truck stop.

Freightliner Cascadia vs. Volvo VNL: Owner-Operator Guide

Compare the new Freightliner Cascadia and Volvo VNL for owner-operators: cabs, engines, safety systems, fuel costs, service access and a practical buying checklist.
A technician inspecting a heavy-duty diesel engine under the raised hood of a semi truck.

How Long Does a Semi-Truck Engine Last? Mileage and Rebuild Signs

Learn what semi-truck engine mileage means, how duty cycle and records affect lifespan, and when to investigate repairs, an overhaul or replacement.
Newer and older semi tractors parked together at a commercial truck dealership.

How Much Does a Semi Truck Cost in 2026? New vs Used

What does a semi truck really cost in 2026? See actual U.S. asking prices, used-truck market data, monthly payments and a simple buyer's budget.
Close-up of the drive-axle differential and suspension underneath a semi truck.

Semi-Truck Axle Ratios Explained: RPM, MPG and Hill Climbing

Understand semi-truck rear axle ratios, calculate cruise RPM using tire revolutions and transmission gearing, and compare highway and hill-duty trade-offs.
A tractor-trailer positioned on a commercial vehicle weighbridge in an industrial yard.

Semi-Truck Axle Weights: Steer, Drive and Trailer Limits

Read semi-truck scale tickets, compare steer, drive and trailer axle weights, understand Interstate limits and plan a safe reweigh before dispatch.
A diesel technician inspecting the exhaust aftertreatment system on a parked semi truck.

Semi-Truck DPF Regeneration: Warning Signs, Cleaning and Costs

Understand semi-truck DPF regeneration, warning lights, soot versus ash, failed regens and service costs. Includes a diagnostic checklist and transparent examples.
The dashboard and manual gear selector inside a heavy-duty semi truck cab.

Semi-Truck Manual vs. Automated Transmission: Cost and Reliability

Compare manual and automated semi-truck transmissions: clutch operation, service intervals, repair risk, fuel use and a worked ownership-cost example.
A white long-haul semi truck pulling a dry van trailer on an open highway at sunset.

Semi-Truck MPG: Fuel Economy Factors and How to Measure It

Measure real semi-truck MPG and understand how speed, weight, wind, idle time, tires and routes affect diesel use. Practical log, calculations and test plan.
A mechanic inspecting the front wheel of a used semi truck while a buyer takes notes.

Used Semi-Truck Inspection Checklist Before Buying

Inspect a used semi-truck before you buy: VIN and title checks, engine diagnostics, brakes, emissions, test drive, DOT records and a true repair-adjusted offer.