Spectrometric analysis is commonly used to detect the presence of metals (elements) which may originate from additives, contamination or wear, in both new and used lubricating oil.
By identifying both the type of metals and their concentration in an oil, it is possible to identify excessive component wear and whether contaminants, such as dirt, water or coolant are present.
Spectrometric analysis can detect metals up to a maximum of 8 microns in size. Larger particles need to be analysed by other methods such as ferrography or PQ Index. Many components are incorporated into a lubricant to impart a wide range of properties.
The laboratory must have up-to-date, comprehensive knowledge of both equipment and lubricants to correctly interpret the source of each metal. Based on this information, the serviceability of an oil can then be calculated.Lubricant Additives
The following is a list of lubricant additives in an oil and their function.
- Detergent: Keeps an engine clean.
- Dispersant: Holds particulates/debris in suspension and prevents their agglomeration.
- Anti-wear: Imparts a thin, protective film to metal surfaces to prevent metal-to-metal contact.
- Extreme Pressure: Imparts a protective film to high pressure areas.
The following is a list of elements or metals in an oil and their function.
- Boron: An element sometimes incorporated in a dispersant. A primary corrosion inhibitor often used in engine coolant.
- Calcium: An alkaline/detergent additive used to neutralise acids which form during the combustion process. Also enhances a clean engine.
- Copper: An anti-oxidant which retards the oxidation process.
- Magnesium: Similar properties to Calcium.
- Molybdenum: A friction-reducer and anti-oxidant.
- Phosphorous: Forms a thin protective layer on metal surfaces similar to Zinc (most EP's are characterised by having a high phosphorous content.)
- Silicon: An anti-foaming agent.
- Sodium: Used in coolants/inhibitor chemicals.
- Zinc: Provides anti-wear, extreme pressure and anti-oxidant qualities.
The following is a list of key elements indicating external contamination of the oil.
- Aluminium: Commonly associated with dirt (approximately one-third to one-quarter the value of silicon.)
- Silicon: A major component in dirt, also a derivative of sealant and gasket materials.
- Sodium: As coolant/chemical inhibitors or salt water contamination in marine applications.