From Blackstone -
"Averages: The universal averages column is the average of all the samples we have analyzed for the particular equipment make and model. The unit/location averages column is your average wear for that particular type of equipment. They are both running averages and change with the number of samples we analyze.
Elements: Elements are quantified in the oil at part per million levels (PPM). This list shows the most common sources of the elements in a gasoline or diesel engine oil.
* Aluminum: Pistons, bearings, cases (heads & blocks).
* Chromium: Rings, a trace element in steel.
* Iron: Cylinders, rotating shafts, the valve train, and any steel part sharing the oil.
* Copper: Brass or bronze parts, copper bushings, bearings, oil coolers, also an additive in some gasoline engine oils.
* Lead: Bearings.
* Tin: Bearings, bronze parts, piston coatings.
* Molybdenum: Anti-wear additive, some types of rings.
* Nickel: Trace element in steel.
* Manganese: Trace element, additive in gasoline.
* Silver: Trace element.
* Titanium: Trace element.
* Potassium: Antifreeze inhibitor, additive in some oil types.
* Boron: Detergent/dispersant additive, antifreeze inhibitors.
* Silicon: Airborne dirt, sealers, gaskets, antifreeze inhibitors.
* Sodium: Antifreeze inhibitors, additive in some gasoline engine oils.
* Calcium: Detergent/dispersant additive.
* Magnesium: Detergent/dispersant additive.
* Phosphorus: Anti-wear additive.
* Zinc: Anti-wear additive.
* Barium: Detergent/dispersant additive.
Physical properties: Viscosity, flashpoint, % fuel and antifreeze,
% water and insolubles are all measured in gasoline and diesel engine oils. If fuel is present in an oil, the viscosity and flashpoint will often be lower than what was stated in the A Values. Insolubles are solid material that is centrifuged out of the oil. They are typically free carbon from the oxidation of the oil itself, along with blow-by past the rings."
Here'* a link