Additives

Doc's Diesel Additives

Targeted Treatments for Trucks That Work.

Today's diesel fuel isn't what your engine was built for. Ultra-low sulfur diesel stripped out the lubricity that protects injectors and fuel pumps, cetane ratings run lower than they should, and modern emissions systems add a whole new list of things that can clog, crystallize, and derate your truck. Doc's Diesel Additives are the fix—a lineup of targeted treatments that put back what the fuel took out, clean up what the miles left behind, and keep hard-working diesels running the way they were engineered to. Every formula has a specific job, and every bottle tells you exactly how to use it.

The Right Treatment for Every Problem.

Think of this collection as a toolbox, not a shelf of miracle cures. For every-tank protection, our 24/7 Diesel Treatment + Cetane Boost raises cetane for faster, cleaner combustion while restoring lubricity and controlling moisture. For deep cleaning, Interval Diesel Treatment goes in every 5,000 miles to knock out injector deposits and asphaltenes, restore spray patterns, and reduce DPF regens—and when symptoms have already set in, our DPF & Injector Fuel Flush is the corrective, single-tank fix. Inside the engine, Oil Friction Treatment cuts metal-on-metal wear and injector stiction with every oil change. Running DEF? DEF Guard stops the crystallization that clogs pumps and triggers derates. And when winter gels your fuel, SOS Cold Weather Rescue reliquefies it and de-ices frozen filters down to -25°F. Want the full strategy in one box? Our bundles—the 1-2 Punch, Long-Haul Protection Kit, Workhorse Kit, and Clean & Protect—pair treatments that work together.

Proven Formulas. Honest Dosing. No Mystery Juice.

The additive market runs on big promises and vague labels. Doc's runs on chemistry and directions you can actually follow. Our treatments are formulated to be safe for all diesel engines—pickups, semis, farm equipment, and off-road machinery—and meet or exceed manufacturer warranty requirements. Our Oil Friction Treatment is ASTM third-party tested for wear protection, and every product page spells out exact dosing: how many ounces, how many gallons treated, and how often to use it. Compatible with ULSD and biodiesel blends, safe alongside your existing maintenance routine, and straight about what each bottle does. No guesswork. No BS.

Doc's Makes It Easy to Build Your Treatment Plan.

Not sure where to start? Match the treatment to how your truck lives. Daily driver or work truck: run 24/7 Diesel Treatment at every fill-up and add Interval Diesel Treatment every 5,000 miles or at every fuel filter change. High-mileage or heavy towing: add Oil Friction Treatment at every oil change. Emissions-equipped truck: keep DEF Guard in the rotation with every DEF fill. Cold country: keep a bottle of SOS on the seat before the temperature drops, not after. Whatever you run—Cummins, Powerstroke, Duramax, or EcoDiesel—there's a Doc's treatment plan that fits.

Free Shipping on All U.S. Orders $99+

Additives are the cheapest protection your diesel will ever get—a few ounces per tank versus a four-figure injector job. Stock a season's worth of treatment, grab a bundle, or add a bottle to your next filter order, and every order over $99 ships free anywhere in the U.S. Small bottles. Big protection. That's the Doc's way.