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AMSOIL Fuel Additives
Specially engineered to provide exceptional all-season protection for a serious performance boost. One dose delivers outstanding detergency, improved lubricity, better cold flow, and higher cetane.
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| Product code | Package size | Unit of measure |
|---|---|---|
| ADBPCN-EA | 8 oz. | 8 oz. |
| ADBCN-EA | 16 oz. | Each |
| ADBHG-EA | 64 oz. | 64 oz. |
| ADBCN-CA | Case of 12 16 oz.s | Case of 12 |
| ADB05-EA | 5 Gallon Pail | 5 Gallon Pail |
| ADB55-EA | 55 Gallon Drum | 55 Gallon Drum |
AMSOIL Diesel 4-IN-1 Fuel Additive (ADB), also marketed as AMSOIL Diesel All-In-One, is a year-round diesel fuel treatment that pairs detergency, cetane lift, lubricity improvement, and cold-flow performance in a single dose. The formula targets owners of pickup trucks, Class 8 tractors, agricultural equipment, marine diesels, and stationary diesel powerplants running on ultra-low-sulfur diesel and biodiesel blends.
High-pressure common-rail injection systems run at 30,000 psi or higher, with internal clearances as tight as 1 to 3 microns. A human hair, by comparison, measures 70 to 100 microns thick, leaving little room for the carbonaceous and internal diesel injector deposits that interrupt spray patterns and rob power. Diesel 4-IN-1 uses a concentrated detergent chemistry that targets both internal and external deposit types, helping restore acceleration, horsepower, and operability while continued use keeps injectors clean.
Cetane number is the diesel equivalent of an octane rating, and a higher number supports a more complete burn. Diesel 4-IN-1 increases the cetane number of the fuel by up to 4 points, improving ignition quality, smoothing idle, reducing smoke and emissions, and supporting easier starting in both heavy-duty and light-duty diesel engines.
Ultra-low-sulfur diesel fuel meets emissions law but strips the sulfur compounds that historically lubricated fuel pumps and injectors. ASTM D6079 testing rates fuel lubricity by wear scar diameter, with the ASTM D975 industry standard capping the wear scar at 520 micrometers and the Engine Manufacturers Association calling for 460 micrometers or better. Diesel 4-IN-1 added to baseline ULSD samples from Colorado, Washington, Delaware, Illinois, Tennessee, Texas, Pennsylvania, North Dakota, and Wyoming brought every sample below both targets in fuel tested in 2017, supporting longer fuel pump and injector life.
As temperatures fall, paraffin wax naturally present in diesel fuel begins to crystallize at the cloud point, then clogs the fuel filter at the cold filter-plugging point (CFPP) measured by ASTM D6371. Diesel 4-IN-1 lowers the CFPP by up to 40 F (22 C) in ULSD, helping prevent gelling and protecting cold-start operability in winter service across the upper Midwest, Mountain West, Canadian Prairies, and similar climates. The additive must be poured in before fuel temperature drops below the cloud point. Once gel or wax crystals form, the additive will not reverse them, and a dedicated rescue treatment is required to restore flow.
Modern diesels return heated fuel from the injection rail to the tank, accelerating the formation of carbonaceous deposits that collect inside the fuel filter and shorten its replacement interval. Diesel 4-IN-1 helps prevent those deposits from settling on filter media, supports a fuel-economy improvement of up to 8 percent through cleaner combustion, and protects metal fuel-system components against corrosion driven by water and acids picked up during fuel transport and storage. The formula is alcohol-free, so it does not introduce moisture-attracting solvents into the fuel.
Diesel 4-IN-1 is recommended for use with heavy-duty and light-duty, on-road and off-road, and marine diesel engines, including Cummins, Power Stroke, Duramax, Detroit Diesel, Mack, Volvo, Caterpillar, and other manufacturers running ULSD, biodiesel blends, or off-road dyed fuel. The maintenance treat rate is one ounce per 2.5 gallons of diesel, which works out to the dose schedule below.
Pour the additive in before filling the tank, and dose only when fuel temperature is above the cloud point. Diesel 4-IN-1 is compatible with all diesel fuels including biodiesel and is alcohol-free. Stacking other aftermarket detergent, cetane, lubricity, or anti-gel products with this formula is not recommended because it can disturb the balanced treat rate among the four functions.
| Property | Value |
|---|---|
| Maintenance treat rate | 1 oz. per 2.5 gal. of fuel |
| Cetane number increase | Up to 4 points |
| Cold filter-plugging point reduction in ULSD (ASTM D6371) | Up to 40 F (22 C) |
| ASTM D6079 wear scar in tested U.S. fuels | Below 460 micrometers |
| Fuel-economy improvement | Up to 8 percent |
| Diesel fuel compatibility | ULSD and biodiesel blends |
| Alcohol content | None |
AMSOIL Diesel 4-IN-1 Fuel Additive is available in an 8 oz. bottle (ADBPCN-EA), 16 oz. bottle (ADBCN-EA), 16 oz. case of 12 (ADBCN-CA), 64 oz. bottle (ADBHG-EA), 5 gallon pail (ADB05-EA), and 55 gallon drum (ADB55-EA). All AMSOIL products are backed by the AMSOIL Limited Liability Warranty. Match the right product in the AMSOIL Vehicle Lookup Guide, review pairing with diesel engine oils in the AMSOIL Diesel Oil Guide, then order AMSOIL Diesel 4-IN-1 Fuel Additive.
I use this all year round in my truck, tractors and mowers. I have never had a single problem. Don't use #1 in the winter I just use 4-in-1.
Would recommend this to a friend.
Just starting using Amsoil 4-1 Diesel fuel treatment based on social media recommendations. Have gone through 3 tanks, every other fill up, and seems my Cummings 6.7 gen-4 with 120k is running a little smoother. However no news is good news in this case.
Would recommend this to a friend.
Product works as should
Would recommend this to a friend.
The maintenance dose is one ounce per 2.5 gallons of diesel. For typical fill-ups that works out to about 8 ounces for a 20 gallon pickup tank, 12 ounces for a 30 gallon tank, and 16 ounces for a 40 gallon tank. The 64 ounce treat-tank size doses up to 160 gallons of fuel.
Yes. The formula is engineered for ULSD-compliant fuel and biodiesel blends used in current emissions-controlled diesel engines, including high-pressure common-rail systems with DPF, EGR, and SCR aftertreatment. It is alcohol-free, so it does not introduce moisture-attracting solvents into the fuel.
Yes. The formula is safe for use in all diesel fuels, including biodiesel blends. Add it to the tank before filling to ensure full mixing with the incoming fuel.
No. Diesel 4-IN-1 must be added at fuel temperatures above the cloud point. Once wax crystals have formed and plugged the filter, this additive will not melt them, and a dedicated cold-weather rescue product or controlled warming of the fuel system is required to restore flow.
Diesel 4-IN-1 combines the detergency and lubricity of AMSOIL Diesel Injector Clean, the cold-flow performance of AMSOIL Diesel Cold Flow, and the cetane lift of AMSOIL Cetane Boost in a single bottle. The combined formula simplifies inventory for fleets, owner-operators, and equipment managers who want year-round protection without juggling three separate products.
Using AMSOIL synthetic lubricants and fuel additives does not void a new vehicle or equipment manufacturer warranty, and all AMSOIL products are covered by the AMSOIL Limited Liability Warranty. Confirm any specific fuel-additive language in the OEM owner literature before use in a vehicle under an active warranty.
For maintenance, dose every fill-up. Year-round use keeps injectors clean, holds cetane and lubricity at improved levels, and maintains the additive package in the fuel system through winter, when cold-flow protection is most important.