Diesel vs. Gasoline Engines: Which Used Engine is Right for Your Truck?

December 23, 2025

Making the Right Choice: Diesel or Gasoline?

When replacing your truck's engine, one of the biggest decisions you'll face is whether to stick with your current fuel type or switch to the other. Both diesel and gasoline engines have distinct advantages and trade-offs, and the right choice depends on how you use your vehicle.

At Used Engines Store, we offer both diesel and gasoline engines for trucks across all major brands. Let's break down the differences to help you make the smartest choice.

Diesel Engines: Built for Power and Longevity

Key Advantages of Diesel Engines:

Exceptional Longevity
Diesel engines are built with heavier-duty components and can easily exceed 300,000-500,000 miles with proper maintenance. If you plan to keep your truck long-term, diesel offers unmatched durability.

Superior Towing and Hauling Power
Diesel engines produce significantly more torque at lower RPMs, making them ideal for:

Towing heavy trailers, boats, or RVs
Hauling construction materials or equipment
Commercial applications requiring constant heavy loads
Off-road and low-speed power needs

Better Fuel Economy
Diesel fuel contains more energy per gallon than gasoline, resulting in 20-30% better fuel economy, especially on highways and under load.

Higher Resale Value
Diesel trucks typically command higher resale prices due to their longevity and capability, making them a better long-term investment.

Diesel Engine Disadvantages:

Higher upfront cost - Diesel engines cost more to purchase and install
More expensive maintenance - Oil changes, fuel filters, and DEF systems add cost
Emissions complexity - Modern diesels have DPF, EGR, and DEF systems that can be costly to repair
Cold weather challenges - Diesel fuel can gel in extreme cold without additives
Noisier operation - Diesel engines are louder than gasoline engines

Gasoline Engines: Affordable and Versatile

Key Advantages of Gasoline Engines:

Lower Purchase and Maintenance Costs
Gasoline engines cost significantly less upfront and have simpler, less expensive maintenance requirements. Oil changes, spark plugs, and routine service are more affordable.

Quieter and Smoother Operation
Gasoline engines run quieter and smoother than diesels, making them better for daily driving comfort and city use.

Better Cold Weather Performance
Gasoline engines start easily in cold weather without gelling issues or block heaters, making them ideal for northern climates.

Simpler Emissions Systems
Modern gasoline engines have fewer complex emissions components than diesels, reducing long-term repair costs.

Wider Availability
More used gasoline engines are available, often at better prices and with more options for your specific vehicle.

Gasoline Engine Disadvantages:

Lower towing capacity - Less torque means reduced towing and hauling capability
Shorter lifespan - Typically last 150,000-200,000 miles vs. 300,000+ for diesels
Lower fuel economy - Especially when towing or hauling heavy loads
Lower resale value - Gasoline trucks depreciate faster than diesel equivalents

Which Engine Type is Right for You?

Choose a Diesel Engine If:

You regularly tow trailers over 7,000 lbs
You haul heavy loads for work or recreation
You drive primarily highway miles (15,000+ miles per year)
You plan to keep your truck for 10+ years or 200,000+ miles
You need maximum torque and towing capacity
You use your truck for commercial or heavy-duty applications

Choose a Gasoline Engine If:

You primarily use your truck for daily commuting and light hauling
You tow occasionally and under 7,000 lbs
You want lower upfront and maintenance costs
You live in extremely cold climates
You prefer quieter, smoother operation
You drive mostly in the city with frequent stops

Can You Switch from Diesel to Gasoline (or Vice Versa)?

Technically possible, but not recommended in most cases. Here's why:

Major Modifications Required:

Complete fuel system replacement (tank, lines, pumps)
Different transmission (diesel and gas transmissions are calibrated differently)
Electrical system modifications (sensors, ECM, wiring harnesses)
Exhaust system changes
Cooling system differences

Cost Considerations:
The labor and parts required to convert fuel types often exceed the cost of simply replacing with the same type. You'll also face potential reliability issues and warranty complications.

Our Recommendation:
Stick with your original fuel type unless you're doing a complete custom build. It's more cost-effective and reliable.

What to Look for in a Used Diesel Engine

If you're buying a used diesel, prioritize:

Mileage under 150,000 (diesels can go much higher, but lower is better)
Compression test results showing consistent cylinder pressure
No visible oil leaks or blow-by
Complete emissions system (DPF, EGR, DEF if applicable)
VIN matching to ensure emissions compliance for your state
Warranty coverage (critical for expensive diesel repairs)

What to Look for in a Used Gasoline Engine

For gasoline engines, focus on:

Mileage under 80,000 for best longevity
Compression test results within manufacturer specs
No visible sludge or contamination
VIN matching for computer compatibility
Warranty protection for peace of mind

Why Buy from Used Engines Store?

Whether you need diesel or gasoline, we provide:

Both fuel types available - Diesel and gasoline engines for all major truck brands
Low-mileage inventory - Quality engines with significant life remaining
Comprehensive testing - Every engine undergoes compression testing and inspection
VIN matching service - Perfect compatibility guaranteed
Up to 3-year warranties - Protection for both diesel and gasoline engines
Nationwide shipping - Fast delivery anywhere in the USA
Expert support - Help choosing the right engine for your needs