by John Evans, WearCheck

In response to an article that appeared in Fin 24 on 15 June this year, Gwede Mantashe, the minister of mineral resources and energy, warned of the use of illuminating paraffin (IP) to doctor diesel in an attempt to defraud the revenue services and increase profits. This article provides some background to this practice, the deleterious affects it can have and the various methods for testing diesel for the presence of illuminating paraffin.

Diesel can be subjected to a variety of chemical and physical tests in the fuels laboratory. One of the most common and important things to look for is contaminants, the most common of which are dirt and water.

Diesel can also be contaminated with other fuels and solvents, in particular illuminating paraffin or IP as it is known. IP is a readily available power source for domestic lighting, heating and cooking. Chemically it is very similar to diesel but because it is used as a domestic power source, it is not subject to the taxes and levies that diesel is, making it  cheaper than diesel to buy.

The less-than-honest members of our society have taken to doping diesel with IP, and because it is so similar (but not exactly the same) to diesel, a diesel engine will run quite happily on a diesel/IP mixture at less than the cost of diesel alone. Although the engine will run without problems in the short term, in the long term the IP will be quite damaging to the engine.

This is because IP has a lower viscosity and less lubricity than diesel and damage will result from increased wear to the components of the fuel system. Although the price difference may not be huge (about R25/l for diesel and about R20/l for illuminating paraffin) if you think of the thousands of litres of diesel used every day, doping diesel with 10% or 20% illuminating paraffin represents a large cost saving for nefarious operators and significant loss of income for the revenue services (SARS).

The effects of IP contamination on diesel are that the viscosity, density and flashpoint will decrease, and the sulphur concentration will increase. IP also has a lower lubricity than diesel. Low viscosity and lubricity mean increased wear of fuel system components. Low density means you get less efficiency, which means that more litres of fuel are required for the same number of kilometres travelled. Low flashpoint could become a safety issue and elevated sulphur could impact the emission controls of modern engines and increase combustion by-products being introduced into the lubricating oil and reducing its ability to lubricate the engine adequately.

Interestingly enough, small amounts of IP may not affect the properties of diesel enough for it to fail the Bureau of Standards specification SANS 342 so, IP can be present, yet the fuel will still pass the specifications of SANS 342. In fact, IP is often legally added to diesel in small amounts by the refineries as it helps prevent the diesel from waxing (freezing) during the cold winter months in-land. But doping diesel with IP, in the long term, is not a good idea and it is also illegal.

Because this type of doping represents a loss of income for SARS, a chemical marker has been added to illuminating paraffin sold in South Africa. The marker comes from Authentix, an American company which specialises in brand protection and anti-counterfeiting. This marker is added to IP at a precise concentration before the product leaves the refinery.

It is possible to test for this marker using a lateral flow test kit, similar to those used for testing for Covid or even pregnancy. The result is a simple yes or no: the marker either was or was not detected. The test kit is very easy to use and takes hardly any time at all. What it cannot tell you is how much IP is present. What is important to mention, is that if the IP came from a source which was not marked, for example, from across our borders, where markers are not used, then no marker will be detected, yet the sample could still be contaminated, but not by enough to fail the other physical tests of viscosity, density and flashpoint that may be carried out.

Further testing is possible, however. The diesel sample can be sent to a SARS-approved laboratory, where a gas chromatography – mass spectroscopy instrument may be used. This instrument can measure the actual amount of the marker in the fuel and, from that, it is possible to calculate the actual amount of IP in the diesel fuel.

The reason for having two levels of testing is because (at the time of publishing), the lateral flow test kits cost about R500, whilst the actual percentage test costs around R5500 (more than ten times the lateral flow test) and has to be outsourced.

Although it is possible for gas chromatography to be carried out on the suspect diesel sample to look for IP itself, because of the very similar physical and chemical characteristics of the two liquids and the large number of compounds in each, the process is slow, expensive and not particularly accurate.

Other contaminants

Whilst on the topic of contaminants in diesel, it is important to take a quick look at the other contaminants which can be found in diesel and can have a deleterious effect on the fuel’s performance.

The two most common contaminants are dirt and water. Contamination from these two sources is usually a matter of poor hygiene practice, as they enter the diesel through the supply train. Diesel leaving the refinery will be clean and dry, but transport, storage, dispensing and use all introduce sources of contamination.

Dirty diesel can cause increased abrasive wear of injectors and fuel pumps, while water can cause corrosion of fuel system components. There are many companies which can remediate, or clean contaminated diesel and it would be hoped that the engine’s on-board fuel filtration system would go some way to keeping harmful contaminants away from sensitive mechanical components.

The other ‘contaminant’ which should be considered is sulphur. Sulphur containing compounds are naturally occurring in diesel but are removed during the refining process as sulphur can poison catalytic converters found on most modern diesel engines. High sulphur can also have an effect on combustion by-products entering the engine oil and reducing its ability to lubricate the engine adequately. The testing for the IP marker is fairly straightforward, easy and cheap to carry out, however, sulphur testing requires sophisticated laboratory instrumentation.

South Africa produces three grades of diesel containing either less than 10 ppm, 50 ppm or 500 ppm of sulphur. Diesel (and other fuels) coming into the country from over-border sources may not be subject to our laws restricting the amount of sulphur present in the diesel and represent a hazard to both the lubrication of the engine and the operation of emission control components.

It is wise to keep your diesel clean and dry and not to pollute it with foreign compounds which could cause engine damage as well as being illegal.

Should you think your diesel is dirty or has been doctored, please contact the nearest WearCheck laboratory right away.

John Evans is a diagnostics manager at WearCheck.

Contact WearCheck, Phone 031 700-5460, support@wearcheck.co.za , www.wearcheck.co.za