Diesel Cold Flow Improver (ACF)
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AMSOIL Cold Flow Improver (ACF) has been reformulated to provide maximum cold flow capabilities
in diesel fuels. The new formulation provides superior performance over the former DFF formulation, which is
available while supplies last.
Cold Weather and Diesel Fuel
As the temperature drops, the wax naturally found in diesel fuel begins to form crystals. The point at which wax
crystals form is known as the cloud point. These wax crystals eventually clog the fuel filter and starve the engine
of fuel or prevent it from starting. While low-quality fuels may form wax crystals in temperatures as warm as 40°F
(4°C), most fuels have a cloud point near 32°F (0°C).
#1 Diesel Fuel
One traditional solution to cold-weather problems in diesel engines is the use of #1 diesel fuel, which is diesel
fuel diluted with kerosene. While #1 diesel fuel has an advantage in low temperature operability, there are also
several disadvantages. The energy content of #1 diesel fuel is about 95 percent of #2 diesel fuel, resulting in
reduced fuel economy and less horsepower. In addition, the kerosene used in #1 diesel fuel provides less
lubrication for the fuel pump and fuel distributor, increasing the likelihood for wear on these critical
Cold Weather Performance Parameters
There are several areas of diesel fuel improvement touted by various cold flow additive manufacturers, including
pour point, cloud point and cold filter plugging point (CFPP). Many claims can be misleading, so it is important to
understand this terminology in order to determine which products truly provide superior performance.
It is important to distinguish between CFPP and pour point. Many competitive products make great
claims regarding pour point, leading consumers to believe their products are superior when they actually have an
inferior CFPP. Once fuel surpasses its cloud point, the wax crystals begin to clog the fuel filter. The CFPP
temperature is a more important characteristic than pour point because the engine will not run if fuel cannot pass
through the fuel filter.
AMSOIL Cold Flow Improver
AMSOIL Cold Flow Improver provides superior fuel flow to help prevent filter plugging in cold temperatures. It is
formulated for a broad range of diesel fuels, including #1 diesel fuel, #2 diesel fuel, biodiesel and hard-to-treat
ULSD fuels. AMSOIL Cold Flow Improver minimizes the need for blending standard #2 diesel fuel with lower quality #1
diesel fuel, helping maintain fuel economy and keep engines functioning normally. It is also excellent for use with
home heating oil and kerosene heat systems.
AMSOIL Cold Flow Improver uses a jet-fuel-type deicer that disperses water to control ice
formation throughout the fuel system. It inhibits wax crystal formation and can improve diesel pour point by as
much as 58°F (32°C), allowing fuel to flow to the engine more easily and improving diesel engine reliability in
cold temperatures. In addition, AMSOIL Cold Flow Improver lowers the CFPP by as much as 34°F (18°C) in ULSD.
Concentrated ACF vs. ACF Blended with Fuel
The new formulation of AMSOIL Cold Flow Improver will show no signs of solidifying in its concentrated state in the
bottle until the temperature reaches -22°F (-30°C), a great improvement over the previous formulation, which
solidified in the bottle at 0°F (-18°C). Cold Flow Improver will only freeze in its concentrated state, and AMSOIL
recommends storing it at temperatures above 0°F (-18°C). If ACF is allowed to freeze in the bottle it can be thawed
and used. When mixed with diesel fuel, ACF effectively improves diesel fuel cold temperature properties. It is
recommended, however, that fuel be treated at temperatures above 32° F (0°C). ACF will not dissolve wax crystals
which have already formed in the fuel.
AMSOIL Cold Flow Improver is specifically formulated for improving fuel flow, helping maintain fuel integrity and
preventing the clogging of filters and injectors. It is excellent for use with diesel fuels, heating oils and
kerosene. Two oz. of AMSOIL Cold Flow Improver treats five gallons of fuel, or one 16 oz. bottle for 40 gallons.
The clear bottles feature an easy-to-read graduation label for accurate dispensing, helping ensure proper treat