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Supplier: Clean Oil Services By: R Smith
21 April, 2010

One of the most commonly asked questions regarding wear metal analysis is "What do the spectrographic analysis numbers mean in wear metal analysis"?

This is a course subject on its own, and will vary in every different type of unit.

Mostly the concentrations of the elements are expressed in Parts Per Million (PPM) or occasionally as percentages. These elements will give us a guide to the origin of the wear metals.

Very briefly, they go roughly like this:

Wear Metals

  • Iron
    Cylinders, crank, gears, roller bearings, camshafts, gears, rings and valves.

  • Lead
    Bearings (white metal), additives, bushing or petrol.

  • Tin
    Bearings (white metal), bushing and piston skirts.

  • Copper
    Bearings, bushes, thrusts washers, gears, brasses, bronzes and additives.

  • Aluminium
    Pistons, washers, housings, bushing and clay dust.

  • Chromium
    Hardening material from cams, rings, rollers, valves and shafts.

  • Nickel
    Hardened or stainless steel shafts, valves and roller bearings.

  • Vanadium
    Used with chrome coating and on valve stems etc.

  • Titanium
    Aircraft components and lightweight, high strength parts.

  • Silver
    Bearings, ring coating in some early engines and solder.


  • Silicon
    Dust, sealant and gasket material, coolant and anti-foam additive.

  • Sodium
    Coolant additive, salt water contaminant or detergent additive.


Additives are added to base oil to enhance the properties of the oil for different uses, and consequently are a helpful identifier to check for cross contamination and in some cases contamination levels.

  • Calcium
    Usually high in engine oils as TBN, detergent or dispersant additives.

  • Magnesium
    Detergent, dispersant additives (higher in engines).

  • Boron
    EP and coolant additive.

  • Manganese
    Detergent additive and lightweight metal.

  • Phosphorous
    Anti-wear additive.

  • Molybdenum
    Anti-wear additive with extremely low co-efficient of friction.

  • Zinc
    Anti-wear, EP and anti-rust additive.

  • Sulphur
    Naturally occurring in base oil, anti-wear additive, extreme pressure additive and combustion by-product.

Remember when interpreting spectrographic results, it is important to monitor the trend of the elements rather than the actual elemental levels.

Check and stay below the manufacturer's recommended limit but be alerted of a pending problem whenever wear trends move by more than 10% over similar oil hours ... always sample on a consistent and regular basis to maintain accurate trends - the key to a successful program.