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  • Writer's pictureScott Irwin

Proper Fuel Maintenance for Optimal Performance

Updated: Nov 5, 2021

- Excerpted from my article published in Pacific Maritime Magazine Jan 2019


Fuel system maintenance is critical for extending engine reliability and performance, whether on the road or on the water. A good fuel supplement should be considered as part of your diesel engine maintenance program.

Diesel Engine Fuel System Diesel fuel has several different roles in the diesel engine fuel system besides providing the energy source. These include the following.

Lubrication - Diesel fuel has lubricating properties and lubricates all the moving components in the engine fuel system, such as fuel pumps and injector pump assemblies. Lubrication in the fuel system is critical for reducing wear and ensuring reliability for long life.

Cooling - Fuel circulates through the fuel system and absorbs the heat generated by the engine. The heat in the fuel is then dissipated as it is recirculated back through the fuel service tank. Without proper cooling, oxidation of the fuel can occur, as well as causing a higher viscosity which can further hinder the fuel’s lubricating ability.

Cleaning - Diesel fuel picks up unwanted contamination in the fuel system as it circulates through the engine fuel system. These contaminants are then removed by the filtration system. Having a quality filtration system is a must for the very strict tolerances of the engine fuel system components.

Diesel Fuel Challenges

Water - A big challenge with marine diesel engine operations is water. Water can come from the fuel supplier, fuel storage tanks or through condensation. Condensation occurs when air enters through the tank vents and meets the warmer fuel in the service tank. Water can settle in the tank or become emulsified within the fuel and become difficult to remove.

Oxidation - Whether it is petroleum diesel, biodiesel or a blend, diesel fuel has been subjected to high temperature processing. While all are likely hydro-treated for finishing and to remove sulfur, without additional protection diesel fuels slowly degrade when stored for extended periods of time.

Weather - Cold weather operations present additional challenges to a diesel engines fuel system. Water that is present in fuel can form ice crystals, restricting fuel flow. In low temperature operations fuel gelling and wax formation is a factor to be aware of, as well as cold filter plugging. All of which can inhibit fuel flow through the engine.

Ultra-Low Sulfur Diesel - Diesel Engines are undergoing radical design changes, and at the same time the fuel industry is also subject to new EPA mandates, requiring sulfur to be removed. With so many simultaneous challenges occurring with both fuel systems and fuel, it’s not surprising to find some unintended consequences.

Ultra-Low Sulfur Diesel (ULSD) is number 2 diesel fuel with a maximum allowable limit of 15 parts-per-million of sulfur. While reducing sulfur significantly reduces emissions, ULSD brings with it several performance challenges for the end user. The most significant challenges of ULSD fuels are insufficient lubricity, lack of BTU content, moisture content control and cold weather performance.

Minimal lubricity additives are added as a requirement by ASTM D975. ULSD has a higher wax content, which increase the possibility of filter plugging in cold weather. ULSD also has less solvency, which reduces its ability to keep the fuel system clean by carrying away deposits.

Fuel Additives

All these challenges lead to an increased need for fuel performance supplementation.

When choosing a winterization additive, there are three key tests that marketers may mention: pour point, cloud point and cold filter plug point (CFPP). While each of these can be a positive indication of improved low temperature diesel performance, the most important test of the three is the CFPP test. It is the most severe and most representative of in-service performance.

Diesel doesn’t readily mix with water, yet it can carry low concentrations as dissolved or emulsified water. Detergent and dispersants keep the water droplets dispersed and very small, thereby protecting injector tips from damage. If water contamination was not identified in advance, a diesel winter additive containing an alcohol-type antifreeze to melt the ice back into water form is recommended.

Also, having a cetane booster for cold weather starts and improved performance is a definite advantage.

Full Torque Diesel Fuel Improver from Lubrication Engineers is a cetane-boosted, detergent-containing formulation that increases power, improves fuel economy, reduces emissions, and provides smoother performance year-round in diesel engines. It is available in winter (W) and summer (S) versions.

Full Torque’s cetane booster increases a fuel’s cetane number by up to three numbers, resulting in faster ignition time, more power, easier starts and less smoke at startup. This hard-working diesel supplement is also loaded with special detergents that keep injector systems clean and working at maximum performance, as well as ingredients that protect against wear, water and corrosion. Full Torque has been formulated to work with today’s biofuels, ULSD fuels and renewable diesel fuels.

Full Torque has been put through rigorous field-testing in the sub-zero temperatures of the north slope of Alaska with outstanding results. Fuel system maintenance is critical for extending engine reliability and performance. A good fuel supplement should be considered as part of your diesel engine maintenance program.

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