Sources of Boron
Boron is an additive metal commonly used in detergent additives and occurs in some EP or AW additive chemistries. Only when the boron 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.
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.
Boron may also due to a coolant leak, often in conjunction with sodium and/or potassium; these elements are present due to the additives used in many coolant formulations. The presence of these elements alongside detected glycol and water often indicate a severe or bottom-end leak, but the absence of glycol and water typically represent a top-end leak where the liquid portion of the coolant is being combusted or boiled out of the system.
On rare occasions, sodium may be present in the form of an oil additive, which can be verified with a sample of new oil for reference.
Watch for the next article in the Elemental Spectroscopy blog series: Lithium.
