Spot the Signs of Red Diesel (Gas Oil) Fuel Contamination and Weather Damage
Red diesel (gas oil) differs in seasonal specification. Its fuel properties are adjusted seasonally to maintain good low-temperature performance and operability.
Winter fuel can be used all year round as it is more resistant to cold (-12°C CFPP min). Whereas summer fuel is only certified for use during the warm months as it has a limited resistance to cold (-4°C CFPP min).
Winter gas oil is refined so that its low properties suit the area and period to be used. However, in periods of severe cold weather, the same issues can occur, including:
• Wax paraffin formation – crystals begin to form when red diesel becomes too cold and amalgamate which block the fuel filter. This will cause the engine to fail or stop due to fuel starvation.
• Contamination – when the temperature drops water can form in the fuel which can clog filters and also cause engine problems.
To find out more about the potential problems of red diesel in the cold months, read our winter blend vs summer blend guide on the Crown Oil website.
The above issues can cause big problems, which is why it’s vital to follow our recommendations to ensure you get the most out of your fuel this winter.
Manage your fuel
Summer quality fuels must not be kept in engines as winter embarks.
If you have any leftover summer grade fuel and you fill your tank with winter fuel on top, you may deteriorate the cold weather characteristics of the winter grade diesel and likely experience undesirable machinery or equipment failure.
Summer quality fuels must not be kept in engines as winter embarks. If you have any leftover summer grade fuel and you fill your tank with winter fuel on top, you may deteriorate the cold weather characteristics of the winter grade diesel and likely experience
Make sure the entire volume of the tank meets the winter spec ahead of the winter period. To avoid winter waxing problems, we suggest you plan ahead and change over from summer to winter fuel by at least June. If you have any concerns regarding your red diesel storage, our team of experts are happy to help. Call us on 0330 123 3399
Shelter fuel tanks and engines
One of the most effective measures you can take to reduce paraffin crystal formation is to ensure your fuel is safe from contamination via safe storage of your fuel. Fuel containers and engines left exposed at night will cool quickly, so storage in a shed or undercover is strongly recommended to help avoid heat loss and paraffin problems.
Likewise, changing the fuel filter will help as a blocked filter will be less tolerant to small amounts of wax crystals.
Insulate tanks, filters and facilities
Another measure to take is to ensure effective insulation of tanks, filters and facilities. This is a cost-effective way to reduce waxing and expensive downtime.
• Clean the tank vent pipe to enable it to breathe
• Remove any water in the fuel from condensation in tanks as this can freeze from 0°C and cause clogging of filters and pipes
• Protect equipment from wind as it cools faster if unsheltered
• Get your fuel tested regularly – paraffin crystals can settle, agglomerate and accumulate in the bottom of the tank and stop red diesel from being pumped
• Only require one delivery per year? Replenish your stocks during the winter season as this grade fuel can be used all year round
• A minimum storage and handling temperature between 0°C and 5°C is recommended where extreme cold is expected
• Insulate above ground storage and handling equipment
• Insulate exposed tanks, pipes and pumps
Use winter-appropriate lubricants
Lubricants and oils are important for cold weather operation. If the wrong oil is used, the engine will be less protected from friction and corrosion which can cause start-up problems.
If an engine oil experiences dilution by the fuel, sufficient wax may build up in the lubricating oil and cause it to solidify in cold weather.
Be sure to check the oil is liquid on the dipstick before starting. If you’re unsure, always change the oil prior to travelling into severe cold weather conditions.
The use of additives can help improve the cold resistance of off-road red diesel, but please note, they must be supplied by an official supplier. If you use the incorrect additive, it can have an adverse effect and cause complications such as haze and water suspension.
How do additives work?
Cold additives (Middle Distillate Flow Improvers) don’t dissolve paraffin crystals that have already formed in the red diesel. They work by modifying the crystal structure to ensure they decrease in size and don’t build up and form larger crystals which block the filters.
Additional additives must only be added when the fuel temperature is higher than the crystal formation temperature (cloud point) otherwise they will not be able to alter the crystal structure.
The problem is, however, that during the production of red diesel, additives are already used to improve cold properties but in an extremely controlled environment at elevated temperatures. This makes it tricky to gauge whether cold flow properties can be improved or not.
The additive must be fully mixed to guarantee a regulated blend and any secondary treatment must be pre-diluted and free-flowing.
Case by case
Each case must be evaluated individually because the existing additive may have exhausted the sensitivity and response of the fuel to further additive treatment.
For fuel that does not contain any cold flow additive, the cloud point and CFFP results will be very alike. The cloud point for fuel that contains additives tends to be around 10°C above the CFPP level, which is why a waxy appearance might transpire when fuels are below the cloud point.