The problem with Diesel Fuel

Automologist, MAC, explains why we get inconsistent diesel fuel quality at the pump, and he offers a winning solution.

Judging by some of the emails I receive, there are a lot of motorists throughout Asia that are experiencing unsatisfactory performance from their diesel-fueled vehicles. There seems to be a general dissatisfaction with the smoothness of the engine and a distinct lack of power from the engine. There is a simple reason for this and it is all to do with the gradual change in the fuel that they are pumping.

The sulphur in the diesel acts as a lubricant and does not burn; instead it enters the atmosphere as sulphur dioxide and ends up as acid rain. In most countries around the world, there has been a slow but steady move from diesel to low-sulphur diesel (LSD) (500ppm of sulphur) and now to ultra-low sulphur diesel (ULSD) (50ppm of sulphur); this has created a lot of problems and rumours in the market, specifically the concern that ULSD has a lower lubricity and cetane rating, which could affect diesel engines and fuel systems designed before 2007.

Oil companies try to convince diesel owners that proper lubrication formulas are added to the fuel before it reaches the pump. Still, many drivers of pickups and especially those in the trucking industry are sceptical as they experienced a drop in fuel economy after the switch to ULSD.

Cetane ratings. Diesel engines operate just fine on cetane ratings between 40 to 55, only that the ignition delay becomes shorter with a higher number, and the more complete and efficient the combustion cycle becomes. The cetane number in ULSD varies between 40 to 45 cetane; the inconsistent cetane ratings at the pump means that diesel users experience inconsistent fuel mileage.

The truth is that most modern diesels can and will run on a range of cetane ratings; in fact, this is one of the 'pros' of the diesel engine. However, the 'cons' will be an obvious reduction in fuel efficiency and parts lifespan, particularly in the combustion side of the engine. During the refinement process of ULSD, in which the fuel is flooded with hydrogen to remove sulphur, much of the lubrication properties as well as the cetane content are removed; the result is cetane numbers that aren't consistent. This means that each time diesel owners fill up at the pump, the quality of the fuel differs.

Lubricity. ULSD has been blamed for premature fuel system and engine wear because of its low sulphur content. Pre-2007 diesel vehicles were designed to run on LSD, but ULSD contains only a fraction of the sulphur concentration. This factor is thought to be one of the main causes of fuel-related problems in diesels.

Bio-mass additives. There is more and more bio-mass being added to the fuels that we are pumping throughout the region. This may seem like the right thing to do for the environment, but when it comes to your vehicle, there are some causes for concern. When diesel fuel sit around in storage, some oxidation will occur which will allow the formation of gums. In addition to this, the biomass added to diesel is naturally hygroscopic; normal fuels will absorb approximately 60 ppm of water and bio-fuels will absorb up to 1500 ppm of water. Furthermore, there will normally be about a 10% drop in the fuel’s calorific value. 

Enough of bad news yet? I hope so! Recently I heard of a sales-rep from a major oil company telling consumers that they should put a beaker of cooking oil into their fuel tanks each time they fill up to make their diesel engines run smoother – sounds to me like he should be taken out the back and shot!

To overcome the constraints of the new diesel fuel that we buy at the pumps, the clever folks over at the X-1R Corporation has introduced a new product called X-1R Diesel System Cleaner. This product has been specifically formulated to be a low-cost solution providing effective lubrication coupled with a controlled action detergent to keep the combustion side of the engine in tip top condition. The product will effectively clean, lubricate and protect the entire combustion side of the engine; it will clean away all gum, water, varnish, particulate contamination and old carbon deposits, whilst effectively lubricating fuel pumps and injectors.

Sounds like good news to me. 

image: imgkid.com