AMSOIL Diesel 4-IN-1
AMSOIL Diesel 4-IN-1 is an all-season diesel fuel additive that cleans injectors, improves fuel lubricity, increases cetane and provides cold-flow protection in one treatment.
Quick Answer
Diesel 4-IN-1 combines the functions of injector cleaner, lubricity additive, cetane booster and preventative diesel cold-flow treatment. AMSOIL recommends it for heavy- and light-duty, on-road, off-road and marine diesel engines.
What Does AMSOIL Diesel 4-IN-1 Do?
AMSOIL Diesel 4-IN-1 combines the detergency and lubricity functions of Diesel Injector Clean, the cold-flow and anti-gelling functions of Diesel Cold Flow and the cetane-improving functions of Cetane Boost in one product.
It is designed for routine preventative maintenance in diesel fuel systems, including modern high-pressure common-rail systems where deposits and inadequate fuel lubricity can affect injector and pump operation.
- Cleans dirty diesel injectors
- Lubricates pumps and injectors to reduce wear
- Extends fuel-filter life
- Improves fuel economy up to 8% according to AMSOIL testing
- Combats fuel-system corrosion
- Prevents wax settling during storage
- Increases cetane up to 4 points
- Safe for diesel fuels including biodiesel
- Alcohol-free
Four Functions in One Diesel Fuel Additive
Cleans Injectors
Targets internal diesel injector deposits and traditional carbonaceous deposits that can interfere with injector operation, fuel atomization and combustion.
Improves Lubricity
Adds lubricity to diesel fuel to help reduce wear in fuel pumps and injectors, including components that depend on the fuel itself for lubrication.
Boosts Cetane
Increases cetane by up to four points to improve diesel ignition quality, starting, available power and combustion performance.
Helps Prevent Gelling
Improves cold-flow performance by controlling wax crystals that can restrict or plug diesel fuel filters as temperatures fall.
How Much AMSOIL Diesel 4-IN-1 Should You Use?
AMSOIL publishes the following maintenance treatment rates for Diesel 4-IN-1. Add the product before filling the fuel tank.
| Diesel 4-IN-1 | Diesel Fuel Volume |
|---|---|
| 2 oz. (59.1 ml) | 5 gal. (18.9 L) |
| 4 oz. (118.3 ml) | 10 gal. (37.9 L) |
| 8 oz. (236.6 ml) | 20 gal. (75.7 L) |
| 12 oz. (354.9 ml) | 30 gal. (113.6 L) |
| 16 oz. (473.2 ml) | 40 gal. (151.4 L) |
| 64 oz. (1.9 L) | 160 gal. (605.7 L) |
Different tank size? Use the diesel fuel additive calculator to calculate the treatment amount for your fuel volume.
Use Diesel 4-IN-1 Before Wax Crystals Form
Diesel fuel naturally contains paraffin wax. As fuel temperature falls, wax crystals begin forming at the fuel's cloud point. Those crystals can eventually accumulate in the fuel filter and restrict fuel flow.
AMSOIL states that Diesel 4-IN-1 can lower the cold filter-plugging point by up to 40°F (22°C) in ultra-low-sulfur diesel fuel.
ASTM D6079 Lubricity Improvement
AMSOIL tested Diesel 4-IN-1 using ASTM D6079, which measures wear scar diameter. Lower wear-scar measurements indicate improved lubricity.
In the fuel samples published by AMSOIL, Diesel 4-IN-1 reduced the wear-scar measurement in every tested fuel. Examples include Colorado fuel improving from 530 µm to 389 µm, Washington from 535 µm to 327 µm and Wyoming from 509 µm to 349 µm.
The AMSOIL bulletin notes that ASTM D975 specifies a wear scar below 520 µm, while the Engine Manufacturers Association specifies a target below 460 µm.
ASTM D6371 Cold Filter-Plugging Point Testing
AMSOIL also tested Diesel 4-IN-1 using ASTM D6371 cold filter-plugging point testing. The published results compare untreated diesel fuel with the same fuel treated with Diesel 4-IN-1.
The test series showed significant cold-flow improvement across multiple U.S. diesel fuels. AMSOIL reports CFPP improvement of up to 40°F (22°C), depending on the base fuel.
Why Injector Cleanliness Matters
High-pressure common-rail diesel systems can operate at injection pressures of 30,000 psi or higher. The injector components needed to maintain those pressures use extremely tight clearances, making deposit control increasingly important.
Internal injector deposits can interfere with injector needle movement, while external deposits can form at the injector nozzle. AMSOIL Diesel 4-IN-1 is formulated to target both internal diesel injector deposits and traditional external carbonaceous deposits.
More Than Injector Cleaner and Anti-Gel
Fuel-Filter Life
Diesel 4-IN-1 helps protect against carbonaceous deposits that can collect in diesel fuel filters and contribute to premature filter plugging.
Fuel-System Corrosion
AMSOIL includes fuel-system corrosion protection among the product's published benefits.
Wax Settling
Diesel 4-IN-1 is formulated to help prevent diesel-fuel wax from settling during storage.
Biodiesel Compatible
AMSOIL states that Diesel 4-IN-1 is safe for use in all diesel fuels, including biodiesel.
Where Can AMSOIL Diesel 4-IN-1 Be Used?
AMSOIL recommends Diesel 4-IN-1 for heavy- and light-duty diesel engines in on-road, off-road and marine applications.
- Diesel pickups
- Heavy trucks and commercial vehicles
- Agricultural equipment
- Construction and off-road equipment
- Diesel generators and stationary equipment
- Marine diesel engines
What Diesel 4-IN-1 Will Not Fix
Diesel 4-IN-1 is a fuel-treatment and preventative-maintenance product. It should not replace mechanical diagnosis when the engine has an actual fuel-system failure.
- It cannot repair a mechanically or electrically failed injector.
- It cannot repair a failed high-pressure fuel pump.
- It cannot repair leaking fuel lines, fittings or seals.
- It cannot replace a damaged or severely plugged fuel filter.
- It will not reverse diesel gel after wax crystals have formed.
AMSOIL Diesel 4-IN-1 FAQ
What does AMSOIL Diesel 4-IN-1 do?
AMSOIL Diesel 4-IN-1 cleans diesel injectors, improves fuel lubricity, increases cetane and improves cold-flow performance in one all-season fuel treatment.
Does AMSOIL Diesel 4-IN-1 clean injectors?
Yes. AMSOIL states that Diesel 4-IN-1 targets internal diesel injector deposits and traditional carbonaceous injector deposits.
Does Diesel 4-IN-1 improve fuel lubricity?
Yes. AMSOIL ASTM D6079 testing shows reduced wear-scar measurements in treated diesel fuels, indicating improved lubricity.
How much does Diesel 4-IN-1 increase cetane?
AMSOIL states that Diesel 4-IN-1 can increase cetane by up to four points.
Is Diesel 4-IN-1 an anti-gel?
Yes. It provides preventative cold-flow protection and can lower cold filter-plugging point by up to 40°F (22°C), depending on the fuel.
Can Diesel 4-IN-1 fix fuel that has already gelled?
No. AMSOIL states that Diesel 4-IN-1 must be added above the fuel's cloud point and will not reverse gel or wax crystals once they have formed.
Can Diesel 4-IN-1 be used with biodiesel?
Yes. AMSOIL states that Diesel 4-IN-1 is safe for use in all diesel fuels, including biodiesel.
Buy AMSOIL Diesel 4-IN-1
Use one treatment for injector cleanliness, added lubricity, cetane improvement and preventative cold-weather protection.