Using the Right Diesel Fuel for Your Truck

Understanding Diesel Fuel Grades

#1 Diesel vs. #2 Diesel

The most common diesel fuel types in North America are #1 Diesel and #2 Diesel, also referred to as Diesel 1D and Diesel 2D respectively.

• #1 Diesel has a lower viscosity and contains less energy per gallon, but it flows better in cold temperatures. It's often used in winter climates or blended with #2 Diesel to create a winterized mix.
• #2 Diesel is more energy-dense and cost-effective, making it the industry standard for heavy-duty trucks in most conditions.

In California’s warmer climate, #2 Diesel is typically the go-to fuel. However, truckers heading into colder states during winter months should consider blending in #1 Diesel to avoid gelling issues.

Ultra-Low Sulfur Diesel (ULSD)

Modern emission standards require trucks to use Ultra-Low Sulfur Diesel (ULSD), which contains no more than 15 ppm of sulfur. Sulfur reduction helps protect after-treatment systems like Diesel Particulate Filters (DPFs) and Selective Catalytic Reduction (SCR) systems. Using high-sulfur diesel in ULSD engines can cause massive compliance failures and component damage.

The Role of Diesel Additives

Diesel fuel additives can be either preventive or performance-enhancing. Here are the most common types:

• Cetane Boosters: Increase ignition speed, improving combustion and cold-start performance.
• Anti-Gel Agents: Prevent fuel gelling in cold weather by lowering the pour point.
• Lubricity Additives: Restore lubricating properties lost in ULSD, protecting injectors and fuel pumps.
• Stabilizers: Extend shelf life and prevent microbial growth in stored diesel.
• Detergents: Clean fuel system components, particularly injectors, to maintain spray pattern and efficiency.

Proper additive use ensures cleaner combustion, better mileage, and fewer regeneration cycles for the DPF.

Fuel System Compatibility

Common Rail Injection Systems

Most modern trucks, especially those built post-2010, utilize common rail fuel injection systems, which operate at extremely high pressures. These systems demand ultra-clean fuel and are sensitive to impurities.

Contaminated or off-spec fuel can lead to:

• Clogged injectors
• Premature wear of fuel pumps
• Incomplete combustion
• Increased emissions and DPF clogging

Using certified ULSD from reputable stations and periodically replacing fuel filters is critical to system longevity.

Biodiesel Considerations

California encourages the use of biodiesel blends, commonly up to B20 (20% biodiesel, 80% petroleum diesel). While biodiesel is renewable and reduces certain emissions, it also presents challenges:

• Higher susceptibility to microbial contamination
• Gelling at higher temperatures than petroleum diesel
• Potential material compatibility issues in older trucks

If running biodiesel blends, ensure your truck's manufacturer approves the specific ratio. Regularly inspect filters and water separators to prevent blockages.

Cold Weather Fuel Strategies

Diesel gelling becomes a real concern when fuel temperatures drop below 15°F.

Preventative tips:

• Use winterized diesel (blended with #1 Diesel)
• Add anti-gel additives proactively
• Keep fuel tanks full to reduce condensation
• Store trucks indoors when possible

A gelled fuel system can cause no-start conditions, fuel starvation, and injector damage—none of which you want on a freezing morning.

The Dangers of Off-Road Diesel in On-Road Trucks

Off-road diesel, often dyed red, is chemically similar to ULSD but lacks road taxes. Using it in on-road applications is illegal and heavily fined. Even accidental contamination—say, by refueling from an off-road tank—can result in state and federal penalties if detected during an inspection.

If you're operating agricultural or construction equipment, off-road diesel is acceptable. But for your on-road rig? Stick with taxed, clear ULSD from authorized sources.

Monitoring Fuel Quality on the Road

Trucks cover thousands of miles weekly, refueling at various stops. Not all diesel is equal, and it's smart to monitor fuel quality through:

• Fuel sampling kits (especially when storing bulk diesel)
• Water separation filters to catch condensation
• Telematics systems that monitor fuel usage and injector performance

Noticing a drop in MPG, sluggish acceleration, or excessive smoke? Poor-quality fuel could be the culprit.

Fuel Economy vs. Engine Longevity

Some drivers may chase better fuel economy by trying unconventional blends or skipping additives. However, long-term reliability and regulatory compliance outweigh small savings at the pump.

Investing in quality fuel and additives supports:

• Longer injector life
• Cleaner after-treatment system performance
• Fewer DPF regenerations
• Better uptime and lower maintenance costs

Choose Diesel the Right Way

Make the right choice at the pump every time, and you’ll extend your engine life, cut down on repairs, and stay compliant with today’s stringent regulations. If you’re unsure what’s best for your fleet, consult your manufacturer’s fuel guidelines—or stop by for an expert inspection and fuel system check.