Modern ultra-low sulfur diesel (ULSD) is cleaner for the environment, but the desulfurization process also strips away natural lubricity. That means today's diesel fuel is harder on fuel pumps and injectors than the high-sulfur diesel of decades past. The right additive can restore lubricity, clean injectors, boost cetane, and protect your engine year-round.
Whether you fill up at Costco diesel stations or anywhere else, here are the best diesel fuel additives we recommend for 2026.
Hot Shot's Secret Diesel Extreme is our top pick for most diesel owners. It's a complete fuel system treatment that cleans injectors, boosts cetane, adds lubricity, and stabilizes fuel. One treatment every 10,000 miles keeps your fuel system in top shape.
Works well with all diesel engines including Ford Power Stroke, Chevy Duramax, Ram Cummins, and VW/Audi TDI engines.
Power Service Diesel Kleen is the gold standard for injector cleaning. It's available at most auto parts stores and is especially good if you're experiencing rough idle, reduced fuel economy, or failed emissions due to dirty injectors.
When temperatures drop below freezing, diesel fuel can gel — paraffin wax crystals clog fuel filters and leave you stranded. Diesel 911 is an emergency de-icer and anti-gel treatment that:
If you live in a cold climate or drive through Montana, North Dakota, or Canada during winter, this is essential gear.
Opti-Lube XPD consistently wins independent lubricity testing. If you have an older diesel (pre-2007) with a VP44 or CP3 pump, or if you just want maximum protection for your high-pressure fuel system, XPD is the top choice.
Howes Diesel Treat is affordable, widely available, and does the basics well. It's a reliable choice for fleet operators and high-mileage drivers who want lubricity and moisture control without breaking the bank.
If you drive a modern diesel (2010+) and fill up at high-volume stations like Costco, you may not need an additive for day-to-day driving. All on-road diesel meets minimum lubricity and quality standards.
However, additives are worth considering if:
| Need | Best Pick |
|---|---|
| All-around protection | Hot Shot's Secret Diesel Extreme |
| Dirty injectors | Power Service Diesel Kleen |
| Cold weather anti-gel | Power Service Diesel 911 |
| Maximum lubricity | Opti-Lube XPD |
| Budget / fleet | Howes Diesel Treat |
Fill up at Costco diesel stations for the cheapest fuel, then add your favorite treatment. The combination of low-priced diesel and a quality additive gives you name-brand performance at warehouse prices.
Check our road trip essentials for more diesel-owner gear recommendations.