AMSOIL Diesel Cold Flow Fuel Additive
AMSOIL Diesel Cold Flow (ADD) is a concentrated winter cold-flow improver for diesel fuel, formulated to lower the cold filter-plugging point (CFPP) of #1 and #2 ultra-low-sulfur diesel (ULSD) and biodiesel before temperatures drop into the wax-formation range. The alcohol-free formula combines a cold-flow improver with a wax anti-settling component that modifies wax crystals so they pass through the fuel filter instead of plugging it. Diesel Cold Flow is built for owner-operators, fleet diesel pickups, agricultural and construction equipment, and stationary fuel tanks operating in northern climates and at high elevations.
Lowers the cold filter-plugging point in ULSD
As temperatures drop, the wax that occurs naturally in #2 diesel begins to crystallize. Most fuels reach their cloud point near 32°F (0°C), and lower-quality fuels can begin clouding as warm as 40°F (4°C). Once wax falls out of solution, the crystals collect on the fuel filter, starve the engine of fuel, and prevent a cold start. Diesel Cold Flow lowers the cold filter-plugging point (CFPP) by up to 40°F (22°C) in ULSD measured by the ASTM D6371 cold filter-plugging point test, extending the temperature range over which a treated fuel will continue to flow through the filter media.
Wax anti-settling chemistry for storage and standby use
Standard cold-flow additives modify the growth shape of wax crystals, but during long static storage, even modified crystals can settle to the bottom of a tank and concentrate at the pickup tube. Diesel Cold Flow uses a wax anti-settling component that drastically reduces crystal size and resists settling, so wax stays suspended and continues to pass through the filter instead of building up at the suction line. This protects diesels that sit between weekend uses, equipment in seasonal storage, and on-farm or jobsite tanks that hold treated fuel through a winter.
Reduces the need to blend #1 diesel
Blending #2 diesel with #1 diesel is a traditional cold-weather strategy because #1 diesel has better low-temperature operability, but #1 diesel carries roughly 95 percent of the energy content of #2 diesel and costs more at the pump. Drivers running heavy #1 blends typically see reduced fuel economy and less horsepower in the same engine. Treating #2 diesel with Diesel Cold Flow minimizes the need to step up to a #1 blend, helping diesel engines hold their normal power and mileage through winter operation.
Inhibits fuel-filter icing
Free water in a diesel tank can freeze on the fuel filter media in cold weather and block flow even before any wax appears. Diesel Cold Flow includes an advanced deicer that helps keep small amounts of water from forming filter-plugging ice, which improves cold-start reliability on diesel systems exposed to humid summer storage or repeated condensation cycles inside a partially full tank.
Compatible with ULSD, biodiesel, kerosene, and heating oil
The alcohol-free formula is safe for use in all diesel fuels, including #1 and #2 ULSD and biodiesel blends. The same chemistry is suitable for heating oils and kerosene, so a single product covers on-highway diesel pickups, off-road equipment, marine diesels, and stationary tanks. Diesel Cold Flow is designed to be used together with AMSOIL Cetane Boost for cetane and ignition quality and AMSOIL Diesel Injector Clean for injector deposit control, so a single tank can carry cold-flow protection alongside cetane and detergency.
Recommended applications and treat rate
Diesel Cold Flow is a preventive winter fuel treatment. It must be added at temperatures above the diesel fuel cloud point, before any wax has crystallized. It will not reverse gel or melt wax crystals once they have already formed; for fuel that has already gelled or for thawing a frozen fuel filter, AMSOIL Diesel Recovery is the correct product. Add Diesel Cold Flow before filling the tank so it mixes thoroughly into the incoming fuel at one of the labeled treat rates:
- 1 oz. treats 5 gallons of diesel.
- 2 oz. treats 10 gallons of diesel.
- 6 oz. treats 30 gallons of diesel.
- 16 oz. treats 80 gallons of diesel.
Diesel Cold Flow is suitable for #1 and #2 ULSD, biodiesel blends, off-road diesel, heating oil, and kerosene in passenger and heavy-duty diesel pickups, Class 8 tractors, marine diesels, agricultural tractors, construction equipment, and stationary fuel storage. The product itself should not be stored below 0°F (-18°C). Confirm fuel and emissions-system compatibility for the specific engine through the AMSOIL Vehicle Lookup Guide before first use.
Order AMSOIL Diesel Cold Flow Fuel Additive
Diesel Cold Flow is available in a 16 oz. bottle (ADDCN-EA), case of twelve 16 oz. bottles (ADDCN-CA), and 5-gallon pail (ADD05-EA) for shop and fleet use. Using AMSOIL synthetic lubricants and fuel additives does not void a new vehicle or equipment manufacturer warranty, and Diesel Cold Flow is backed by the AMSOIL Limited Liability Warranty. Match the right diesel oil and emissions-system spec for the engine with the AMSOIL Diesel Oil Guide, match the right product in the AMSOIL Vehicle Lookup Guide, then order AMSOIL Diesel Cold Flow Fuel Additive.
Customer reviews
I have used this for many years on & off the farm, have not
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.
By Thomas from Nebraska on June 26, 2026.
Would recommend this to a friend.
New to the product
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.
By Joe from Gardnerville NV on March 05, 2026.
Would recommend this to a friend.
Works
Product works as should
By Todd on March 02, 2026.
Would recommend this to a friend.
Read all 308 reviews
Frequently asked questions
When should Diesel Cold Flow be added to a diesel tank?
Add Diesel Cold Flow before fuel temperatures drop into the cloud-point range, ideally before filling the tank so the additive disperses into the incoming fuel. The treatment must be in the tank while the fuel is still above its cloud point. Once wax has already crystallized or fuel has gelled, Diesel Cold Flow will not reverse it, and AMSOIL Diesel Recovery is the correct product for thawing a frozen fuel filter or de-gelling a stalled tank.
How much Diesel Cold Flow per gallon of diesel?
The labeled treat rate is 1 oz. per 5 gallons of diesel fuel, roughly a 1:640 ratio. A 16 oz. bottle treats 80 gallons, a 6 oz. dose covers 30 gallons, and a 2 oz. dose covers 10 gallons. Pre-measure the dose, pour into an empty or near-empty tank, then fill with diesel so the additive disperses uniformly through the load.
Is Diesel Cold Flow safe for biodiesel and ULSD?
Yes. The formula is alcohol-free and is safe for use in #1 and #2 ultra-low-sulfur diesel (ULSD) as well as biodiesel blends. It is also suitable for heating oils and kerosene, which makes the same product useful for stationary tanks and off-road equipment alongside on-highway diesel pickups and Class 8 tractors.
Can too much Diesel Cold Flow be added to a diesel tank?
Diesel Cold Flow is engineered to perform at the labeled 1 oz. per 5 gallon treat rate, and overdosing does not deliver additional cold-flow improvement beyond the design point of the additive package. Stick to the labeled treat rate, and step up to a higher-volume product code such as the 5-gallon pail (ADD05) when treating large equipment, fleet vehicles, or stationary tanks instead of over-treating with multiple smaller doses.
Does Diesel Cold Flow boost cetane or clean injectors?
Diesel Cold Flow is a dedicated cold-flow improver and wax anti-settling additive, not a cetane booster or injector detergent. For cetane and ignition quality, pair it with AMSOIL Cetane Boost. For deposit control on injectors and intake-side hardware, pair it with AMSOIL Diesel Injector Clean. The three products are designed to be run together when cold-flow protection, cetane, and detergency are all needed in the same fill.
Does pump diesel already contain anti-gel?
Many fuel suppliers blend a winter package into pump diesel during cold months, but treat levels and CFPP performance vary by region, season, and supplier, and untreated #2 diesel is still common at non-winterized stations and in summer-stocked tanks. Adding Diesel Cold Flow at the labeled treat rate provides a known, measurable level of cold-flow improvement on top of whatever the supplier may have added, and is especially useful when pulling fuel from older stock, off-road tanks, or stations outside the winter blending window.
Will running Diesel Cold Flow void a diesel engine warranty?
No. Using AMSOIL synthetic lubricants and fuel additives does not void a new vehicle or equipment manufacturer warranty, and Diesel Cold Flow is covered by the AMSOIL Limited Liability Warranty.
