AMSOIL DIESEL 4-IN-1 FUEL ADDITIVE

AMSOIL Diesel 4-IN-1 Fuel Additive combines the cleaning power of Diesel Injector Clean, the cold-weather protection of Diesel Cold Flow, and the performance gains of Diesel Cetane Boost into a single treatment that covers your diesel engine year-round. One dose at every fill-up keeps injectors clean, fuel flowing in freezing temperatures, and combustion quality at its peak.

Modern diesel fuel doesn't do your engine any favors on its own. Ultra-low-sulfur diesel (ULSD) stripped away much of the natural lubricity that fuel pumps and injectors rely on. High-pressure common-rail systems operate at 30,000 psi and above, with internal clearances as tight as 1 to 3 microns. Deposits that would be invisible to the naked eye can cause injector sticking, reduced power, higher emissions, and premature component failure. Add cold weather and low-quality fuel into the mix, and you're dealing with gelled filters, hard starts, and lost efficiency all at once.

CLEANS INTERNAL AND EXTERNAL INJECTOR DEPOSITS
Most diesel fuel additives were designed for older, traditional injector systems. They don't address the internal diesel injector deposits that form inside the tighter tolerances of high-pressure common-rail engines found in trucks like the Ram 2500 Cummins, Ford 6.7L Power Stroke, and Duramax-equipped GM diesels. AMSOIL Diesel 4-IN-1 uses advanced chemistry that targets both internal deposits on injector pintals and traditional carbonaceous deposits on nozzle tips. Restoring injectors to like-new condition improves spray patterns, fuel atomization, and combustion efficiency. With regular use, it keeps them clean and can improve fuel economy by up to 8 percent, potentially offsetting the cost of the additive itself.

SIGNIFICANT LUBRICITY IMPROVEMENT ACROSS U.S. DIESEL FUELS
ULSD meets a bare minimum standard for lubricity, and many fuels barely clear that bar. The ASTM D975 diesel fuel standard requires a wear scar below 520 microns in ASTM D6079 testing. The Engine Manufacturers Association and Canadian standards push for 460 microns or less. AMSOIL tested baseline diesel fuels from nine states, including Illinois, Delaware, Colorado, Washington, Tennessee, Texas, Pennsylvania, North Dakota, and Wyoming. Untreated fuels showed wear scars ranging from 484 to 551 microns. After treatment with Diesel 4-IN-1, wear scars dropped to between 327 and 397 microns across all nine samples. That puts every treated fuel well below even the stricter EMA threshold, giving your fuel pump and injectors the protection ULSD alone cannot provide.

LOWERS COLD FILTER-PLUGGING POINT BY UP TO 40°F
Wax crystallization in diesel fuel is the primary cause of clogged fuel filters and no-start conditions in cold weather. Most diesel fuels reach their cloud point near 32°F, and once wax crystals form and accumulate in the filter, the engine is starved of fuel. AMSOIL Diesel 4-IN-1 lowers the cold filter-plugging point (CFPP) by up to 40°F (22°C) in ULSD. Testing across fuels from Illinois, Delaware, Colorado, Ohio, Utah, Kansas, and Wyoming showed consistent CFPP reductions, with treated fuels reaching as low as -41.8°F (-41°C). This is meaningful protection for anyone running a diesel truck, tractor, or piece of equipment through a northern winter. The additive also prevents wax settling during storage, which matters for seasonal equipment and backup generators. It must be added before the fuel reaches its cloud point, as it will not reverse gelling once crystals have formed.

INCREASES CETANE UP TO 4 POINTS
Low-cetane fuel burns less completely, leading to rough idle, increased smoke, sluggish throttle response, and harder starts. Diesel 4-IN-1 raises cetane by up to 4 points, improving ignition quality so combustion is more complete and efficient. The result is smoother idle, reduced smoke and emissions, faster starts in cold and warm conditions, and maximum available horsepower from each combustion event. For diesel owners towing heavy loads or running at sustained high output, that improvement in combustion quality translates directly to better throttle response and cleaner exhaust.

EXTENDS FUEL FILTER LIFE
Modern diesel engines return hot fuel to the tank, which promotes the formation of carbonaceous deposits that collect in the fuel filter and cause premature plugging. Diesel 4-IN-1 protects against these deposits, keeping filters cleaner longer and reducing unscheduled maintenance. For fleet operators or anyone running high annual mileage, fewer filter changes add up quickly.

COMPATIBILITY AND USAGE
AMSOIL Diesel 4-IN-1 is safe for use in all diesel fuels, including biodiesel. It is alcohol-free. It is recommended for use in all heavy-duty and light-duty diesel engines, on- or off-road, and marine diesel applications. This includes popular platforms like the 6.7L Cummins, 6.7L Power Stroke, 6.6L Duramax, and 3.0L EcoDiesel, as well as agricultural and construction equipment.

TREAT RATE
Use one ounce per 2.5 gallons of fuel. For a standard 40-gallon truck tank, one 16-ounce bottle provides the correct treatment ratio with an up to 4-point cetane increase.