As winter approaches, diesel fuel users need to take steps to prepare their fuel for cold weather conditions. Diesel fuel can gel and freeze in cold temperatures, which can lead to a host of problems such as clogged fuel filters and lines. By winterizing or treating diesel fuel, users can prevent these issues and keep their vehicles and equipment running smoothly all winter long.
What causes diesel fuel to gel in winter?
Diesel fuel contains paraffins, which are waxy hydrocarbons that naturally occur in crude oil. At warm temperatures, paraffins remain dissolved in the fuel. But as temperatures drop, the paraffins begin to crystallize and cluster together. This causes the fuel to take on a cloudy appearance and thicken. Eventually, if the temperature gets low enough, the wax crystals will clog fuel filters and fuel lines, preventing the engine from getting the fuel it needs.
The temperature at which diesel fuel starts to gel is referred to as the “cloud point.” This is the point where paraffin crystals first become visible as the fuel is cooled. The actual point at which fuel will clog filters happens at the “cold filter plug point” (CFPP) which occurs at a slightly lower temperature after more wax has crystallized. So winterizing diesel is all about lowering these temperature points to prevent gelling and clogging issues.
Should you use #1 or #2 diesel in winter?
There are two main grades of diesel fuel – #1 (winter grade) and #2 (summer grade). The difference lies in the chemical composition:
- #1 diesel has a lower viscosity and lower cloud point/CFPP than #2
- #1 diesel contains less paraffin wax and more volatile compounds like kerosene
- #2 diesel has a higher energy density (BTU output) than #1
Since #1 diesel contains less wax and flows better in cold, it is the preferred fuel for winter use. The reduced paraffin content allows it to remain liquid at much lower temperatures. Most experts recommend switching to #1 or a blend once temperatures consistently drop below 32°F (0°C).
However, #1 is not always readily available in all regions. So #2 diesel can be used in winter with proper fuel additives or treatment to improve flow. It also may require swapping out the fuel filter for a heated model to prevent wax from clogging the filter material. The fuel filter on a diesel vehicle is the most important item to address when preparing for cold weather.
Should you use diesel fuel additives in winter?
Diesel fuel additives, often called anti-gels, can provide an alternative or supplement to switching to winter grade diesel. Additives work by altering the wax crystallization process in one of two ways:
- Depressants – These additives lower the temperature points at which wax begins to from in fuel by disrupting paraffin crystal formation.
- Dispersants – These additives cause wax crystals to remain tiny and widely dispersed rather than clustering together into larger gels.
Using additive products can significantly improve the cold flow properties of diesel fuel. Many popular winter diesel additives combine both a depressant and dispersant into one formula. The dosage is then optimized depending on outside air temperatures.
One important note is that additives are more effective at preventing gelling issues versus resolving issues once they have occurred. So it is best to treat tanks early before temperatures drop if relying on additives alone.
Recommended diesel winter additives
Some of the most popular diesel winter additive brands include:
- Howe’s Lubricator Diesel Treat
- Power Service Diesel Fuel Supplement + Cetane Boost
- Stanadyne Performance Formula
- Lucas Oil Diesel Deep Cold
Always follow the dosage instructions based on tank capacity and outside temperature. Most recommend adding the additive each time new fuel is purchased in winter. The additive concentrates will blend with the fresh fuel and remain potent over time.
Steps for winterizing diesel fuel supply
Here is a summary of the key steps involved in properly winterizing a diesel fuel supply:
- Choose winter-grade diesel – Use #1 diesel or a blend if temperatures will be below 32°F (0°C) for extended periods. This may require locating a supplier that provides winter grade fuel.
- Consider fuel additives – Use a diesel anti-gel additive to enhance cold flow, especially if using #2 diesel in frigid conditions. Follow dosage instructions.
- Replace fuel filter – Swap out the factory fuel filter for one with a built-in electric heater. This prevents wax from clogging the filter.
- Add heated fuel lines – Run heated fuel lines from the tank to engine if operating equipment in extremely cold arctic conditions.
- Insulate fuel tank – For large outdoor stationary tanks, enclosing or burying the tank can help modulate temperatures.
- Top off tank – Keep tanks full to reduce condensation which can accelerate gelling. Allow room for expansion if very cold.
It is also important to monitor fuel regularly once temperatures drop. Look for signs of hazy appearance or reduced flow which may indicate the start of gelling issues. Taking corrective action early can prevent major issues down the road.
Steps for treating gelled diesel fuel
If diesel fuel does end up gelling, here are some steps to help get it flowing again:
- Move vehicle/equipment to warm space – Bring it indoors into a heated garage or shop if possible to allow fuel to warm up and thaw.
- Apply localized heat – Use a portable diesel fuel heater or heat lamp to warm the fuel tank and lines. Heating pads can also work.
- Add anti-gel additive – Dose the tank with double the normal amount of winter additive to help break up wax.
- Gently agitate fuel – Rock or tilt vehicles/equipment to loosen gelled fuel and mix in additive.
- Replace fuel filter – A clogged fuel filter will need to be replaced once fuel is flowing again.
Avoid aggressive tactics like hammering on fuel lines or tanks which could damage the system. The key is gradual warming and agitation along with anti-gel chemicals to dissolve away wax deposits clogging the works.
Storing diesel fuel for winter
For storing diesel fuel over the winter months, here are some tips to maintain proper fuel quality and prevent issues:
- Fill storage tanks completely to the top to minimize condensation buildup inside.
- Add a biocide additive to prevent microbial growth which can occur from condensation.
- Consider adding an anti-gel additive as a preventive measure against waxing.
- Store fuel out of direct sunlight and extreme temperature fluctuations.
- Drain water separators regularly to remove any accumulated condensation.
- Rotate stock by adding fresh treated fuel on top to keep additives mixed in.
With proper winterizing preparation and ongoing monitoring, diesel fuel can continue flowing smoothly all season long without cold weather problems. Just remember the keys are using winter grade diesel, fuel additives, heated fuel filters, and keeping water out of tanks and lines.
| Diesel Fuel Type | Characteristics | Best Use |
|---|---|---|
| #1 Winter Grade | – Lower viscosity at cold temps – Lower wax content |
Temperatures below 32°F (0°C) |
| #2 Summer Grade | – Higher energy density – Higher wax content |
Temperatures above 32°F (0°C) |
Conclusion
Winterizing diesel fuel properly is critical for keeping engines running and avoiding downtime issues during cold weather. By taking proactive steps like using winter fuel blends, fuel additives, heated fuel filters, and monitoring fuel quality, diesel equipment can keep operating reliably all winter long. Following the recommendations outlined in this article will help diesel users be prepared for the unique challenges of cold weather fuel management.