Silicon (Si) and
Aluminum (Al)	10 to 30 ppm	Dirt ingestion	Air intake system, oil filter plugging, oil filler cap and breather, valve covers, oil supply
Iron (Fe) 	100 to 200 ppm	Wear of cylinder liner, valve and gear train, oil pump, rust in system	Excessive oil consumption, abnormal engine noise,performance problems, oil pressure, abnormal operating temperatures, stuck/broken piston rings
Chromium (CR)	10 to 30 ppm	Piston ring wear	Excessive oil blow-by and oil consumption, oil degradation
Copper (CU)	10 to 50 ppm	Bearings and bushings wear, oil cooler passivating,radiator corrosion	Coolant in engine oil, abnormal noise when operating at near stall speed
Lead (Pb)*	40 to 100 ppm	Bearing corrosion	Extended oil change intervals
Copper (CU) and
Lead (Pb)*	10 to 50 ppm	Bearing lining wear	Oil pressure, abnormal engine noise, dirt being ingested in air intake, fuel dilution, extended oil drain intervals
Aluminum (Al)	10 to 30 ppm	Piston and piston thrust bearing wear	Blow-by gases, oil consumption, power loss, abnormal engine noise
Silver and
Tin	2 to 5 ppm
10 to 30 ppm	Wear of bearings	Excessive oil consumption, abnormal engine noise, loss in oil pressure
Viscosity Change	 	Lack of lubrication	Fuel dilution, blow-by gases, oil oxidation, carburetor choke, ignition timing, injectors, injector pump, oil pressure
Water/Anti-freeze	 	Coolant leak or condensation	Coolant supply, gasket sealed, hose connection, oil filler cap and breather
* Significant as wear metal, only for engines using unleaded and diesel fuel.