Diesel Fuel Analysis

Diesel Fuel Analysis Service

Our Diesel Fuel Analysis service tests your diesel fuel for: levels of contamination, system wear and its chemical make-up. These tests (detailed below) are performed in laboratory conditions and the findings, along with any recommendations or required actions, will be detailed to you in a comprehensive report.

The FA-ST Complete (UK) Diesel Analysis & Sampling Kit (FUELKIT1) - featured below - is perfect for use to submit your diesel fuel samples to us. The kit can be used with engine, transmission, turbine, gearbox and hydraulic oils. It comes with a pre-paid Jiffy bag and return address label, and is inclusive of the oil analysis service.

Please note the pre-paid Jiffy bag and return address label are not included in our International Lube Oil Analysis & Sampling Kit (OMKLUBE).

Diesel Fuel Analysis Tests Performed

Contamination Testing

Contamination testing is split into a number of different individual test. We will perform:

Particle Counting (ISO)

Particle counting is actually a test for particle contaminant levels and not specifically wear debris. It does not distinguish between wear and dirt particles, but if it can be determined that nonferrous contamination has remained stable, then an increase in the particle count must be attributable to wear. A magnet can be used to modify the particle count to count ferrous debris only. There are various ways of doing this, but essentially a magnet holds back the ferrous debris while the nonferrous debris is flushed from the sample, after which a ferrous debris particle count is performed. Particle counts are invariably reported according to ISO 4406:2017. Other standards do exist, but they are not as commonly used. ISO 4406:2017 returns a three-digit solid contamination code. The method of particle counting is not as important as performing the test properly. It is important to note that only results from the same method should be compared.

ISO 4406:2017 Standard

The ISO 4406:2017/2000 classification of particle contents was introduced to facilitate comparisons in particle counting. Sudden breakdown in a fuel system is often caused by large particles (>14 micron) in the fuel while slower, progressive faults (e.g. wear and tear) are caused by the smaller particles (4-6 micron). This is one of the explanations why the particle reference sizes were set to 4 micron, 6 micron and 14 micron in ISO 4406:2017/2000.

A typical sample of dirty diesel contains in every 1 ml of diesel:

  • 4,500 particles >4 micron
  • 1,200 particles >6 micron
  • 140 particles >14 micron

The diesel sample described above would have a contamination class of 19/17/14 - see Particle Contamination ISO classification table.

Particle Contamination

ISO Classifications

p/ml ISO Code
80,001 - 160,000 24
40,001 - 80,000 23
20,001 - 40,000 22
10,001 - 20,000 21
5,001 - 10,000 20
2,501 - 5,000 19
1,301 - 2,500 18
641 - 1,300 17
321 - 640 16
161 - 320 15
81 - 160 14
41 - 80 13
21 - 40 12
11 - 20 11
5 - 10 10
2.51 - 5 9
1.31 - 2.5 8

Water K.Fischer

The Karl Fischer test measures the exact amount of free and dissolved water molecules contained in the diesel fuel sample. The Karl Fisher test is reported in a numerical value.


All flammable liquids have a flashpoint. It is defined as the lowest temperature at which the liquid can form an ignitable mixture in air. The flammable liquid we are referring to in this case is diesel or petrol, i.e. fuel which has contaminated the oil in an engine. We can also test for diesel fuel which has been contaminated with petrol. All flammable liquids have a vapour pressure. The vapour pressure is closely related to the liquid's temperature. So, as the temperature increases, so does the vapour pressure. When the vapour pressure increases, the concentration of evaporated flammable liquid in the air increases. It is therefore clear tha the temperature determines the concentration of evaporated liquid at equilibrium In essence, the flashpoint is the lowest temperature at which enough fuel vapour exists that it will ignite.

System Wear Testing

The Ferrous Wear Index is used, in a test to indicate the total measure of Iron (regardless of size) in the sample. This technique is used to determine early component wear.

Chemistry Testing

Density/specific gravity/API

The density of diesel fuel varies slightly depending on the ambient temperature. Diesel fuel varies between about 0.81 and about 0.96 between the temperatures of about 15 degrees Celsius and about 25 degrees Celsius. The specific gravity of a liquid is basically the ratio of the density of a substance when compared to a standard. In most cases that standard is water.

FAME Testing

FAME testing tests for the amount of biodiesel in your fuel. Current EU levels are at 7% and anything above this could cause issues for injectors, pumps or filters.

Bug Bactria

Bugs are in cfu/ml Colony forming units per ml.

  • 10-2=100 cfu.
  • 10-4=10000 cfu.
  • 10-7=10000000 cfu.

Fungus is reported as slight, moderate or heavy, because it doesn’t form cfu’s in the same way as bacteria. Yeast behave like bacteria and reported in the same format (i.e. 10-5 cfu). These can clog filters and cause engines to stall.

Diesel Bug Treatment

Diesel Bug Treatment is exactly what the product says. Our diesel bug treatment is a biocide blend formulated especially for preventing or eradicating the fuel spoilage organisms known collectively as diesel bug. A 100ml bottle is sufficient to prevent diesel bug growth in 2000 ltrs of fuel. For serious contamination addition rates of 100ml to 100 ltrs may be required. Very rarely over 15 years of selling the product have we had to clean out a tank but for severe contamination several doses may be required to break up and remove the biological sludge that forms. Our diesel bug treatment disperses into both the water and fuel phases in your tank and will remain sufficiently active for over a year at both high and low temperatures. Marine 16 Diesel Bug Treatment is the fuel treatment of choice for the RNLI, The Royal Marines, Sea Start and River Canal Rescue as well as being number 1 in the Practical Boat Owner magazine review.

Diesel Bug Test Kit

The individually packed Marine 16 diesel bug test-kit can be used to check for microbial contamination of diesel fuels in boats, storage tanks and home heating fuels. The kit contains full instructions of use and results will be returned in approximately 3-4 days.

Featured product

Complete (UK) Diesel Analysis & Sampling Kit (FUELKIT1)

Kit contents

60ml PETG sample bottle, sample tubing, equipment ID labels, re-sealable plastic bag and a pre-paid, addressed postal Jiffy bag to return your sample.

All-inclusive oil analysis service

Price is inclusive of the laboratory oil analysis, recommendations and comprehensive report, which will be issued to you in pdf format via e-mail.

Fast Service Turnaround

Turnaround time from receipt of the sample in our laboratory to return of your initial report and recommendations is 2-3 working days and the bacterial analysis will take another 2-3 days as this is the incubation period. An updated report is then issued.