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How to prevent cold weather issues with diesel fuel

Updated: 7 days ago

How to prevent cold weather issues with diesel fuel
Cold Weather Diesel

Before diesel fuel enters an engine, it passes through a filter to strain out impurities. This filter is an incredibly important part of your engine, but it's also a prime target for cold weather to wreak havoc. A naturally occurring substance in #2 diesel fuel is called paraffin wax. Under normal conditions, this wax remains in liquid form, so it's harmless to your equipment. The problem occurs when cold temperatures cause paraffin wax to solidify and bind together into larger crystals that can't flow through the filter. So when diesel users talk about gelling, they are referring to this issue.

Gelling starts to occur at a specific temperature known as the cloud point.

It is coined after the white haze or "cloud" that appears as paraffin wax crystallizes. For example, #2 diesel fuel has a cloud point of 14 degrees Fahrenheit, or -10 degrees Celsius. If the temperature continues dropping, it will eventually reach a point where wax crystals collect rapidly on the fuel filter, starving the engine of fuel.

This threshold is known as the cold filter plugging point or C F P P (CFPP). This CFPP indicates the lowest possible temperature when a given diesel fuel can still pass through a 45-micron filter. For most #2 diesel fuels, the CFPP is typically within a few degrees of the cloud point. While CFPP is an industry-wide measurement, it can be less accurate for some modern equipment.

Today's high-performance diesel engines require finer filters than those used in measuring CFPP. As a result, a new diesel engine can potentially plug at a warmer temperature than its fuel's documented CFPP. While CFPP can be a helpful measurement in some instances, keep in mind its limitations. It should be noted that both cloud point and CFPP are natural properties of fuel and thus impossible to change. Paraffin wax will always crystalize when the temperature gets cold enough.

So, how then do you stop wintertime gelling and filter plugging? Even though you can't change cloud point or CFPP, there's a third factor you CAN change. The solution to cold-weather gelling and filter plugging lies in one key metric: operability. Operability is defined as the lowest possible temperature a piece of equipment can function at without a loss of power; operability is the variable diesel equipment owners have control over.

But if you can't stop paraffin wax from crystallizing, how is it possible to lower the equipment's minimum operating temperature? Even though you can't get rid of the wax crystals in a #2 diesel, you can change their shape. Therein lies the secret to improving your engine's cold weather operability. A special fuel additive called a cold flow improver, or C.F.I. dissolves the bonds in paraffin wax. It breaks up larger crystals into many smaller parts; a CFI enables paraffin wax to pass smoothly through the filter. Typically, a CFI is effective down to about zero degrees Fahrenheit or -18 Celsius.

The good news is that most fuel companies add C.F.I to diesel fuel in the wintertime. So, you don't need to do anything, but not all companies do this. We have seen customers in southern Texas not have this winterized diesel fuel in the past. Also, you may have summer fuel in your tank that does not contain any CFI's.

There are many cold fuel additives on the market. You may have heard about products such as Diesel 911, Lucas, Kleen-Flo, Hot-Shot and others. If you own any diesel-powered equipment, consider having one of these additives and use it in winter. This stuff works!

Remember, diesel-powered transport trucks operate at frigid temperatures in Northern Canada and Alaska during the winter without issues. They do this by adding CFI's to diesel fuel. So, using a diesel-powered generator in the cold should be no different.

You can do other things to help your engine run in extremely cold temperatures. Many engines already use glow-pugs to aid in cold weather conditions, but adding an oil pan heater, block heater, and battery warmers or chargers also helps.

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