Viscosity is one of the most important characteristics of fluids. It determines the thickness of the film between the components to be lubricated and gives important information on the state of the lubricant during service. An increase in viscosity may indicate oxidative deterioration of the oil or contamination by unburned particles and / or wear metals. A decrease may indicate a fuel dilution. It is therefore a parameter to be kept under control. The measurement of the flow time of the lubricant through a calibrated capillary is carried out in a thermostatic bath at different temperatures, according to the type of oil analyzed. The viscosity degree of the hot lubricant, which for an engine oil is defined by the SAE J300 specification and for a transmission oil by the SAE J 306 specification, is determined with the viscosity at 100 °C. On the other hand, for hydraulic and industrial oils, the degree of viscosity is defined by the ISO 3448 standard and is determined by the viscosity at 40 °C. The AxxonOil laboratory is equipped with two SVM viscometers where the kinematic viscosity is determined at 40 °C and 100 °C (ASTM D-7042). These tools provide maximum flexibility covering the entire range of viscosities, densities and temperatures and deliver results in seconds.

Density is a fundamental physical property that can be used together with other properties to characterize both light and heavy fractions of oil and petroleum products. The determination of the relative density is necessary for the conversion of the measured volumes at the standard temperature of 15 °C. The relative density or specific weight is one of the routine control tests that we run in the blending process. The digital density meter available in AxxonOil allows to measure the relative density not only of petroleum products but also of antifreeze and brake fluids. In combination with other tests, it is also used to characterize unknown oils, as it correlates with the nature of the crude oil source.

The pour point is the minimum temperature at which oil flows. It is determined by cooling a preheated sample at a given rate and examining its flow characteristics at 3 °C intervals. For the user of lubricants, the pour point becomes relevant when low temperatures are such that they affect the flow of the oil. In some industrial applications, it represents a critical value since it identifies the minimum service temperature of the oil. For white oils, the pour point provides a means of determining the type of raw material used for refining and its previous processing history. It also reflects the presence of wax or paraffinic hydrocarbons.

Petroleum products such as new and used lubricants may contain acidic components such as additives or degradation products. The total acid number (TAN) indicates the relative quantity of basic substances necessary to neutralize the acids present in the lubricant and is expressed in mg KOH per g of sample.

Furthermore, TAN is used as a quality parameter of lubricating oils both for the evaluation of new products and as an indicator of degradation of these products during use. This parameter is generally used to determine the quality of new industrial oils and also to determine the contamination and level of oxidation of industrial oils in service.

The total acid number can be determined using the ASTM D-664 method, which consists of a potentiometric titration where the sample dissolved in solvent is neutralized with a standard solution of KOH in isopropyl alcohol.

The total base number (TBN) is one of the main parameters for evaluating the quality of a lubricant, especially in the long term.The TBN evaluates the ability of a lubricant to neutralize acids that are formed during the combustion process. Ultimately it represents a parameter that tells us how much the lubricant’s ability to cancel the effects of these acids is still potentially worth. This parameter is particularly relevant for oils intended for heavy duty given the generally severe service conditions in which these vehicles operate. For the oil to guarantee the necessary protection of the parts, it is essential that the TBN, while decreasing over time, remains at acceptable values. A 50% drop in the TBN value should be considered as a caution level, it indicates that the oil is close to the end of its service life: at this point it is necessary to top up or change the oil. A decrease of 75% is instead a critical limit that can lead to serious damage. If, on the other hand, the TBN is too low, the consequences can also be very serious as some elements of the engine could undergo corrosion and / or sludge.ASTM D-2896 is the suitable method for determining TBN for both new and used oils. This method has been used in studies evaluating the end of life of the engine oil as the test is sensitive to low alkalinity values ​​that would not be readily detectable with other methodologies.

The ASTM D156 method or Saybolt color scale is applicable to refined products that have an ASTM color lighter than 0.5. This method is used for slightly yellowish but low chromium petroleum products such as mineral oil, kerosene, gasoline, naphtha, aviation fuels, white petroleum waxes and pharmaceutical white oils.This color scale ranges from +30 to -16. Pharmaceutical grade white mineral oils which must be clear and colorless (Saybolt +30). The degree of color / transparency is a critical property for white mineral oils which makes them useful in their many cosmetic, pharmaceutical, agricultural, food and industrial applications.On the other hand, the ASTM D-1500 method or ASTM color scale is applied to more colored petroleum products such as lubricants, additives and base oils. It is a color scale ranging from pale straw yellow to deep red in sixteen steps (0.5-8.0 units in 0.5 increments). The visual comparators can reach a resolution of 0.5 units, while the automatic Lovibond® PFX and PFXi instruments in the AxxonOil Laboratory reach a resolution of 0.1.The color of a lubricating oil is not always a reliable guide to product quality and should not be used indiscriminately by the consumer as a purchasing specification.

With the ASTM D-5293 (Cold cranking viscosity or CCS) method, the apparent viscosity of engine oils and base oils is determined using a cold start simulator (CCS) at temperatures between -5 and -35 °C. This method simulates the viscosity of the oil in the crankshaft bearings during cold start, which is one of the requirements specified in the SAE J300 standard that defines the degree of viscosity of the oil. CCS viscosity helps define the “W” or “winter” part of a multigrade oil. As with the kinematic viscosity, SAE J300 defines mandatory ranges that must be met: the lowest “W” level achieved must be declared.

High shear and high temperature viscosities are representative of the conditions encountered in bearings in high performance automotive engines to ensure reliability and fuel efficiency.

The ASTM D4683 method determines the dynamic viscosity of engine oils at 150 °C and the shear rate 1×106 s-1 using a tapered bearing viscometer (TBS viscometer) equipped with a refined thermoregulation system.

With the determination of viscosity at high temperature and high shear rate, it has been possible to establish the minimum shear rate limits for engine oils under severe operating conditions, which have become part of the SAE J-300 engine oil viscosity classification.

While it is in circulation, the oil accumulates deposits resulting from wear and external contaminants.Plasma emission spectrometry rapidly identifies 22 elements in new oils as well as wear metals and contaminants in waste oils. The most analyzed elements are Aluminum, Boron, Barium, Calcium, Chromium, Copper, Iron, Manganese, Sodium, Potassium, Nickel, Phosphorus, Lead, Silica, Tin, Zinc and Sulfur. This analysis determines the quantity of certain additives remaining in the lubricant and therefore indicates the remaining service life of the oil. In addition, AxxonOil also uses ICP-AES during the production of lubricating oils for quality control and compliance with production and industry specifications. Finally, high concentrations of wear metals can indicate abnormal wear or contamination. For this reason, this test method can be used to monitor the condition of a machinery and evaluate when corrective actions are required.

Infrared or IR spectroscopy is an absorption spectroscopic technique normally used in the field of analytical chemistry and the characterization of liquid, solid and vapor phase materials.
ASTM E-1252 qualitative infrared analysis is performed by identifying the functional group or comparing the IR absorption spectra of unknown materials. This method is useful for identifying through the functional group area (3800-1300 cm-1) and the fingerprint area (1300 to 650 cm-1) the composition of lubricants, base oils and the identification of some additives.
Additionally, chemical changes such as oxidation, nitration and sulfonation of lubricants, degradation of anti-wear additives and contamination from moisture, fuel, glycol and dust can be assessed by FT-IR according to ASTM E-2412. In this case, the infrared (FT-IR) spectra are determined and the spectra of the new and used lubricant are comparatively evaluated and the type of degradation or contamination is identified.
The results from ASTM E2412 can be combined with the TAN (total acid number) for industrial oils and the TBN (total base number) for motor oils and viscosity data and provide detailed and extended conclusions on oil quality.
IR analysis is now a routine in the AxxonOil laboratory. It is fast and provides reliable results. Furthermore, by examining an IR spectrum it is possible to obtain a large amount of information on the molecular composition of the sample

Determination of water content by Karl Fisher coulometric titration is a standard method used for the determination of moisture in petroleum products, lubricating oils and additives.

The presence of moisture could lead to corrosion and premature wear due to cavitation resulting in decreased lubrication and premature clogging of the filters. Furthermore, water acts as a catalyst on the aging of additives, generating the formation of insoluble reaction products and favors deleterious bacterial growth.

Knowledge of water content is important in the production, purchase, sale or movement of petroleum products to help predict their quality and performance characteristics.

Coulometric Karl Fischer titration is used for the determination of water in additives, lubricating oils, base oils, automatic transmission fluids, hydrocarbon solvents and other petroleum products. By appropriately choosing the sample size, this test method can be used for the determination of water from mg/kg (ppm) to percent level concentrations.

The pH value is defined as a measurement scale used to express the acidic or basic character of solutions.

A pH less than 7 indicates an acidic solution, while a pH greater than 7 indicates a basic solution. A pH equal to 7 characterizes a neutral solution where the concentration of hydrogen ions (H+) and hydroxyl ions (or hydroxide OH-) resulting from the breakdown of the water molecule (H2O) are equal.

The pH value can be determined using an electronic instrument called a pH meter or pH meter, which is made up of a glass electrode. The inside of the electrode has a glass membrane sensitive to the concentration of hydrogen ions (H+). This probe measures the electrical potential generated by the hydrogen ion (H+) concentration outside the membrane, in reference to a hydrogen ion potential inside the membrane and compared to a standard reference potential.

The pH value is used for quality control of engine coolants and brake fluids.