Marcus Reid

Diesel Technician & Senior Contributor

Marcus spent two decades in independent diesel shops before moving into writing, working mostly on Power Stroke, Cummins and Duramax pickups along with the RVs and farm equipment that came through the same bays. At USA Diesel Finder he covers diagnostics, DPF and emissions systems, and the practical side of choosing a shop — what a fair estimate looks like, which symptoms can wait, and which ones can't. His goal is to give owners enough context to have a confident conversation with their mechanic.

Articles by Marcus Reid

A blue Volvo truck parked outside a warehouse in an industrial area, daytime scene.
Maintenance
7 min read

DEF Crystallization: Why It Happens and How to Avoid It

DEF crystallization clogs injectors, sensors, and pumps in your SCR system. Here's why Diesel Exhaust Fluid crystallizes, what it costs to fix, and how regular checks and fresh fluid keep your emissions system running clean.

Detailed shot of a car's interior highlighting the gauge and air vent.
Maintenance
7 min read

Preventing Diesel Fuel Gelling in Winter: A Practical Guide

Diesel gelling shuts down trucks, RVs, and generators when temps drop fast. This guide covers cloud points, winter-blend fuel, additive treat rates, block heaters, and a cold-weather fuel checklist to keep your rig running through the coldest months.

A man wearing a jacket refuels a truck at a gas station during winter with snow falling.
Maintenance
8 min read

Can Diesel Fuel Go Bad? Failure Symptoms & Warning Signs

Yes, diesel fuel can go bad — usually within 6-12 months once water, oxygen, or microbes get into the tank. Here's how to spot the warning signs before bad fuel wrecks your injectors or fuel pump.

A nuclear power plant in Hameln, Germany, showcasing cooling towers and electricity pylons.
Maintenance
8 min read

Common Issues with Diesel Generators and How to Avoid Them

Diesel generators fail for a short list of predictable reasons: wet stacking from low-load running, fuel contamination, weak batteries, and skipped filter changes. Here's how each problem starts, what it costs to fix, and the maintenance schedule that prevents it.

Mechanic focused on vehicle engine repair in an indoor workshop.
Maintenance
7 min read

How Do Diesel Engines Work? A Plain-English Breakdown

Diesel engines don't use spark plugs — they rely on compression to ignite fuel. Here's a clear, no-jargon breakdown of the 4-stroke cycle, fuel injection, turbocharging, and emissions systems that make diesels different from gas engines.

A large industrial truck parked in an urban setting, showcasing transportation industry visuals.
Maintenance
7 min read

Does Gas and Diesel Mix or Separate? What Happens When Fuels Combine

Gasoline and diesel don't separate like oil and water — they mix completely, and that's the problem. Learn why even a small gas-diesel mix-up can damage injection pumps, what to do if you misfuel, and what it costs to fix.

Close-up of frosty roof shingles showcasing winter's icy grip and cold atmosphere.
Maintenance
7 min read

At What Temperature Does Diesel Freeze? (Gel Point Explained)

Diesel doesn't freeze solid like water, but cold weather can still stop your engine cold. Learn the real cloud point and gel point temps for #1 and #2 diesel, how to spot gelling before it strands you, and what actually fixes it.

Close-up of a green nozzle refueling a white car at a gas station.
Maintenance
7 min read

Is Diesel Cheaper Than Gas? 2026 Price Comparison Guide

Diesel almost always costs more per gallon than gasoline, but that's not the whole story. This guide breaks down 2026 pump prices, fuel economy differences, cost per mile, and when a diesel actually saves you money over the life of a vehicle.

Photograph of stacked shipping containers at a bustling Hamburg port terminal.
Maintenance
7 min read

What Is a Reefer? Refrigerated Trucks and Trailers Explained

A reefer is a refrigerated truck or trailer with its own diesel-powered cooling unit that keeps cargo cold in transit. Learn how reefer units work, what they cost to maintain, and how CARB rules affect older units.