The ICP analysis (Inductive Coupled Plasma) provides information about metal abrasion (wear), additives and other contaminants. The change in additive elements, together with other tests, can provide information about the condition of the used oil.

Diesel fuel in the oil has a negative impact on the lubricating film. The viscosity is reduced. In addition, the positive lubricating properties of the oil additives are affected. The consequences are increased wear and even total failure of the tribological system. Causes for an increased fuel content are e.g. incorrectly adjusted carburetor, defective injection nozzle, or problems in the intake and exhaust tract (clogged air filter, blocked soot filter etc.). The diesel fuel content in the oil can be detected by means of gas chromatography. The figure is given in %.

Fourier transform infrared (FT-IR) spectroscopy can be used to draw conclusions about the oil condition. With known fresh oil, changes in the spectrum can be used to calculate mixtures, water and glycol input, additive degradation, soot content, oxidation and nitration values. If known, please always give us the full name of the fresh oil (manufacturer and exact product name)!

Qualitative determination of the glycol content based on FT-IR spectroscopy. Glycol in the oil is an indicator of leaks in the cooling system (e.g. defective oil cooler or cylinder head gasket). It leads to oil thickening (jelly formation) and can block filters and oil bores.

The Particle Quantifier Index is a dimensionless indication of the amount of ferromagnetic (magnetisable) abrasion in the oil. In contrast to the ICP method, particles larger than 5 µm can also be recognised here. The PQ index therefore also makes it possible to identify wear patterns that are due to short-term effects, for example.

The TBN is an indicator of the alkaline reserve of the oil. In engine oils, it indicates whether the oil is still able to neutralise acidic combustion products that are introduced into the oil via blow-by gases.

Viscosity is one of the most important parameters for defining the lubricating properties of an oil. Changes during operation therefore have a significant influence on the safe operation of the system. Viscosity at 40° C plays a decisive role in the industrial environment in particular, as industrial oils are standardized according to this characteristic value (e.g. ISO VG 32; the viscosity of this oil must correspond to 32 mm/s² (+/- 10 %) at 40° C). However, the viscosity value at 40 °C is also determined for the automotive sector, as the VI can be calculated from this (see VI). If the viscosity changes at 40° C, this can mean mixing with other oils, oil thickening, etc.

The viscosity at 100° C is used to standardize viscosity classes for automotive lubricants (e.g. SAE 40; at 100° C the oil must have a viscosity of 12.5-16.3 mm/s² to comply with the standard). This value is important for industrial oils because the VI can be calculated from the two viscosities (at 40° C and at 100° C).

The viscosity of oils depends on the temperature. Rising temperatures cause a decrease in viscosity, the oil becomes thinner. However, this temperature dependency is not the same for all oils. With high-quality products, this influence is less noticeable, i.e. the viscosity of the oil decreases less with increasing temperatures than with cheaper products. The viscosity index (VI) was introduced to create comparability here. This value is calculated from the viscosity of the oil at 40° C and 100° C. A high VI is to be equated with a low temperature dependency. The VI should not change during operation, as regular oil ageing (oxidation) has the same effect on viscosity across all temperature ranges. However, shearing of special additives to improve the viscosity index (VI improver) can occur. As a result, the VI decreases, whereas an increase indicates mixing during refilling.

The first impression counts. We therefore record its visual appearance as early as the sample registration stage. Abnormalities such as particles, deposits, streaks or phase separation are documented. The sample is then also photographed.

Water is the mortal enemy of every tribological system. The lubricating effect is reduced, there is a risk of cavitation due to the formation of vapor bubbles, oil ageing is accelerated, it has a corrosive effect, etc. The water content in the oil should therefore always be monitored during an oil analysis. A sufficiently accurate and cost-effective method is determination by means of FT-IR spectroscopy. The water content is given in %. If it is necessary to determine the water content more precisely, the measurement is carried out using a titration procedure according to the Karl Fischer method. The water content is indicated on the laboratory report in ppm (parts per million).

While foam forms on the oil and can be measured there, the air separation capacity provides an indication of how quickly air bubbles can be removed from the oil. For this purpose, the density of the oil is measured in relation to the time after air is introduced.

Foam (air bubbles) reduces the lubricating properties of oils, the temperature release behavior deteriorates and oxidation is promoted. Foam is usually caused by mechanical action (meshing tooth flanks) or sudden pressure loss. Aging phenomena favor the formation of foam. However, mixing different oils can also lead to increased foaming. To monitor the foaming behavior, air is introduced into the oil via a porous stone. The height of the foam carpet and its decay (after 10 minutes) are then measured. The measurement can also be carried out at different temperatures (sequence I, II and III) and thus realistically reflects the conditions inside the machine.

MPC stands for membrane patch coloumetry. This method is used to determine the tendency of oils to deposit. In particular, the polar oil ageing products that form during long oil usage cycles can no longer be kept in suspension by the oil after a certain point in time. This results in deposits that restrict the functionality of the system. Vacuum filtration of the used oil via a very fine filter and the subsequent optical measurement of the filter provides an indication of this. Suitable measures, from fine filtration of the entire oil volume to the final oil change, can be derived from this.

RULER is the abbreviation for Remaining Useful Life evaluation routine. Antioxidants can be detected transparently using this procedure. Antioxidants are intended to slow down the regular oil ageing process by neutralizing the free radicals produced in the process. The usual test methods are aimed at monitoring the consequences of oxidation. Using the RULer, the degradation of antioxidants can be monitored directly, allowing countermeasures to be taken at an early stage!

Due to its non-polarity, oil does not combine with the polar water, but instead a phase separation occurs. However, oil ageing products (and also some additives) can influence this, as they are mostly polar in nature and therefore improve the solubility of water in oil. When determining the water separation capacity, the time until phase separation is therefore measured.