How to Keep Diesel Fuel from Gelling

When cold weather starts to approach and temperatures drop, it is critical for diesel operators to keep fuel flowing effortlessly. Diesel fuel contains wax and when temperatures start to become colder, the fuel can start to cloud. Clouding means that the wax starts to form crystals, which can cause filters to clog and create problems in engine performance. If the fuel goes beyond clouding to where it actually gels, then diesel equipment will come to a screeching and abrupt halt. This is why it is important to know how to keep diesel fuel from gelling.

What Causes Fuel Gelling?

Today’s diesel fuel filtering systems can more easily lead to filter clogging due to their far more restrictive design. Modern fuel filters can filter fuel from 10 microns or less. Older style filters had a filtering capability of 25 microns. 10 micron filters, because of their stricter and finer filtering capacity, can easily become clogged when temperatures drop and when cloud points are reached.

What is the cloud point? It is the temperature at which diesel fuel starts to create wax crystals. Because fuel filters have tighter restrictions, the cloud point is a more critical specification than pour point, since the cloud point is reached at higher temperatures. In many diesel units, when a cloud point is reached and solid wax starts to appear, the modern fuel filters start to plug up and equipment starts to fail. The question now arises in how to keep diesel fuel from gelling.

AMSOIL Diesel All-In-One.
AMSOIL Diesel All-In-One

How to Keep Diesel Fuel From Gelling

The most obvious and most effective solution is to treat diesel fuel with a special fuel additive that stops fuel from clouding and gelling. There are specialty blend diesel fuel additives that are engineered exclusively for winter time use. Their chemistry is rather unique in that it can actually control the formation of wax crystals. The chemistry actually works by modifying and changing the size and shape of the wax crystals.

Also, this specialized chemistry literally keeps these modified wax crystals from coming together or combining with each other to form a gel. In other words, it eliminates the possibility of the fuel gelling. Regardless of how severely cold the weather becomes, such a diesel fuel additive keeps the fuel flowing smoothly.

AMSOIL Diesel Cold Flow.
AMSOIL Diesel Cold Flow

For such an additive to be effective, it must be added to the diesel fuel before temperatures start to get cold enough where they could reach the cloud point. Adding such an additive too late is ineffective. Another factor to consider in how to keep diesel fuel from gelling is whether there is gum and varnish buildup within the diesel fuel system. Understand that today’s fuel must deal with a growing problem which is oxidation.

If a fuel oxidizes, the end result is a deposit buildup within the fuel system of varnish and gum. If left unchecked, this varnish and gum buildup can cause clogging within the fuel lines, injector nozzles, and filters. Not only does this result in inferior performance, but also will cause very poor spray patterns from the injector nozzles. If the diesel fuel system is in such poor condition due to clogging as a result of gum and varnish, then come winter time, any wax or gelling will cause problems much faster than a system that is in good condition.

With that said, it is better to choose a fuel conditioner that not only will eliminate wax formation during cold temperatures, but that will help eliminate varnish and gum buildup. The proper chemistry will help the fuel to stay thermally stable, which translates to eliminating oxidation, which finally means the elimination of the potential of gum and varnish buildup.

How to Liquefy Gelled Fuel

If the unfortunate happens and the diesel fuel system does become gelled, at that point the only real solution is to use a quick acting diesel fuel additive designed solely for liquefying any diesel fuel that has been gelled. Think of this additive as an emergency tool. This type of situation usually happens in extremely cold temperatures and with fuel that has not been treated correctly or had an additive that was of inferior quality.

If the diesel engine fails to start, or comes to an abrupt halt, not only is the fuel gelled but most likely the fuel filters and lines are frozen with ice. A high-quality diesel fuel additive formulated specifically to liquefy gelled fuels will react very quickly and will de-ice any frozen fuel filters and lines. This type of additive is extremely concentrated and is engineered to quickly dissolve any wax in fuel tanks, fuel lines, and filters. It literally liquefies the gelled fuel. Also, any ice buildup will also be dealt with and eliminated.

Be careful in the choice of de-gelling additives that you use. The marketplace is full of such additives that are formulated with harmful methanol or ethanol. Such products can cause very serious corrosion and rust issues within the fuel systems. Not only that, they can also adversely affect the flash point of #2 diesel fuel. If such a product were to in fact lower the flash point of the fuel, it could adversely and severely affect engine startup.

AMSOIL Diesel Recovery.
AMSOIL Diesel Recovery

Only choose products that are designed to be 100% safe for diesel fuel systems and that contain no ethanol and methanol. Also, be sure the additive helps the fuel to burn efficiently and does not lower its flash point.

We’ve discussed the various aspects on how to keep diesel fuel from gelling. If one implements the correct preventive maintenance methods for your diesel engine, such problems can be eliminated and stopped before they occur. Simply choose the highest quality diesel fuel treatment specifically formulated for winter use and treat your fuel before the cold weather arrives. Also, it’s a good idea to keep a couple of gallons of a quality de-gelling diesel additive in your vehicle in case of emergencies. A proactive approach will keep your diesel fuel free of wax buildup and of course will eliminate any potential gelling of the fuel.