Sources of Molybdenum
Molybdenum is an additive metal commonly used in friction modifier additives. Only when the molybdenum level deviates more than 25% from the new oil or reference value should a concern be raised, but the likeliest cause is mixing or topping-off with a different product. This type of friction modifier is found in many engine oils and some transmission fluids.
With normal and expected additive depletion due to usage, the additives are still present in the fluid, and will still be measured at their normal levels. Once they do not appear in the fluid, they have dropped out completely, which indicates a more severe degradation mechanism or additive drop-out.
Molybdenum may appear due to wear, as some piston rings and certain alloys of steel use molybdenum. Molybdenum will increase disproportionally with iron in a reciprocating application but will remain proportional with iron with wear of an alloyed part.
Watch for the next article in the Elemental Spectroscopy blog series: Silicon.
