I don’t see people posting up about oil analysis much on this forum, but I thought this information may be helpful as a general guideline for what commonly reported oil analysis items can be attributed to. This information was given to me by a Mobil Signum Oil Analysis rep at some point and I just recently re-discovered it while cleaning my paperwork. I claim absolutely no credit for any of it. Not all of it will apply to your car or your results, and you need to understand that different engines and components can have different wear indicators, but I think it is useful information to help in understanding oil analysis generally.
Metal Analysis:
Aluminum: Pistons, Bearings, Dirt
Antimony: Grease, Bearings
Barium: Additives, Water, Grease
Boron: Coolant, Additives, Salt water
Cadmium: Bearings, Plating
Calcium: Detergent, Dispersant Additive
Chromium: Cylinders, Rings, Gears, Crankshafts, Coolant
Copper: Bearings, Bushings, Bronze, Coolers
Iron: Cylinders, Rust, Crankshaft, Water
Lead: Bearings, Gasoline, Grease, Paint
Magnesium: Additives, Bearings, Sea Water
Molybdenum: Additives, Rings
Nickel: Shafts, Gears, Rings, Turbine components
Phosphorus: Additives, Gears
Silicon: Dirt, Defoamants, Sealants
Silver: Bearings
Sodium: Cooland, Salt Water, Additives
Tin: Bearings, Solder, Coolers
Titanium: Turbine Components, Springs, Valves
Zinc: Additives, Bearings, Plating
Typical wear metals are Aluminum, Antimony, Cadmium, Chromium, Copper, Iron, Lead, Magnesium, Molybdenum, Nickel, Silver, Tin, and Titanium. An increasing trend of one or more of these metals is a warning that abnormal wear may be occurring and corrective action may be needed.
The additive metals blended into the lubricants by the manufacturers are Barium, Calcium, Magnesium, Phosphorous and Zinc. Phosphorous and Zinc are anti-wear metals. Calcium, Barium and Magnesium are detergents and dispersants. They pick up wear and contaminated particles then carry them to the filters for removal.
Boron and Sodium may indicate coolant leaks. Sodium Borate and Sodium Chromate are used as coolant additives. In the event of a coolant leak these trace metals will remain in the lubricant even if the water has evaporated due to operating temperatures.
Physical Properties Analyses:
Viscosity: The viscosity test is an indication of proper lubricant in use, oxidation and contamination such as fuel dilution.
Water: The presence of water in most lubrication systems is abnormal. Possible sources of water are condensation, coolant leaks, and outside contamination.
Solids: This test measures total solids, both suspended and settleable. An abnormal amount of solids in the lubricant could indicate carburization problems if the unit is running too rich or too lean, the oil filter has reached maximum usefulness and is no longer able to remove contaminants, and if the air intake system is not operating properly.
Fuel dilution: Measures the amount of unburned fuel in the lubricant. This test could indicate leaks in the fuel line, carburetor, injectors, and fuel pump.
Glycol: Analysis results are usually reported as Positive or Negative. Glycol present in the lubricant normally indicates a coolant leak. The presence of glycol in a lubricant could cause serious damage to the unit and should be dealt with immediately.
Total acid Number: Indicates acidic products present in the lubricant. High acid numbers usually mean overheated or oxidized oil, etc
Total Base number: Indicates a reserve alkalinity of lubricant. A low TBN indicates a depletion of additives and a low dispersion characteristic.
Oxidation: At elevated temperatures, oil exposed to oxygen from the air will oxidize to form a variety of compounds. The majority of these are carbonyl containing compounds e.g. carboxylic acid.
Nitration: Nitration products are formed during the fuel combustion process in internal combustion engines. Most nitration products are formed when an excess of oxygen is present. These products are highly acidic, form deposits in combustion areas, and rapidly accelerate oxidation.