Helpful Information To Prevent Gelling In Your Diesel

Helpful Information To Prevent Gelling In Your Diesel

Published by Opti-Lube on Dec 1st 2015

Are you ready for winter?

Make sure you and your investments are protected this winter with Opti-Lube Fuel Additives. Refineries make sure their diesel fuel meets minimum low temperature specifications based on location and time of the year. However unseasonably cold snaps, long distance travel from a warm location to a cold location, or just extreme low temperatures can cause issues for many drivers. One of the main issues is gelling. Cold Flow Improvers are designed to help ULSD improve low temperature flow performance. When considering why a fuel gels there are four cold flow measurements/terms that are useful to know.

Cloud Point (CP) -

The temperature at which waxes become visible in diesel.

Cold Filter Plugging Point (CFPP) -

The highest temperature at which a fuel will not flow through a filter or requires more time than is allotted to flow through the filter.

Pour Point (PP) -

The highest temperature at which the diesel fuel will not flow.

Operability -

The lowest temperature at which a diesel fuel vehicle will operate in practical application. Typically either 18°F below the cloud point or the CFPP Temperature, whichever is higher.


WHY DOES FUEL GEL? All diesel fuel contains waxes. Protect yourself and your investment When the waxes are warm, as in from gelling. milder climates, they stay liquid and are harmless. As they cool, the waxes begin to crystallize and link together. A visual haze known as the Cloud Point begins to appear in your fuel. As temperatures continue to fall, sheets of crystallized waxes form and begin to stack on top of each other, creating more solid layers that can block filters, stopping the flow of fuel to the engine. Eventually as the fuel becomes more gel-like, the Cold Filter Plugging Point is reached and fuel flow will stop altogether.


As the name suggests, works to counteract the gelling of diesel fuel. Typically speaking, there are two kinds of anti-gel, Preventative and Post CFPP. Post CFPP Anti-gels are used after gelling or plugging has already occurred. They are often alcohol or kerosene based to burn through the waxes and restore fuel flow. Although use of these chemicals is sometimes necessary, such as when gelling and plugging has already occurred, alcohol and kerosene based additives are usually avoided. The speed by which alcohol or kerosene can liquefy wax buildup is useful but the lack of lubricity, and the caustic effect these chemicals have on rubber seals and hoses, is why they are typically avoided. Preventative Anti-gels are used before gelling occurs. To ensure a Preventative anti-gel works properly there is an important rule to keep in mind. Diesel Fuel can not be at or below the cloud point when Preventative anti-gel is added.

There are two reasons for this: (1) If the fuel is cold and wax has begun to crystalize and link, the cold flow additive will not be able to modify the crystals as designed to minimize their growth or alter their morphology and (2) cold fuel has poor solubility, meaning proper mixing can not occur. The easiest way to ensure your preventative additive is properly mixed and your diesel is not too cold during winter months is to add it at the pump while fueling. Once mixed properly the preventive anti-gel will not only do its job but will not ‘fall out’ of solution or separate.

Opti-Lube XPD and Winter contain components that interact with the wax molecules in a way that prevents them from stacking and subsequently forming large, filter plugging crystals. As the temperatures drop this season, ask yourself: Am I ready for winter?