Wear Elements

Iron can be present as fine particles produced by abrasion or wear, but also as iron oxides associated with the presence of water or a corrosive reaction to additives. Iron generally comes from the liners in engines or from hydraulic cylinders, pumps, lines and reservoirs in hydraulic systems and from planetary gears and carriers in final drives and differentials.

Chromium is a very hard metal wear particle produced by engine piston rings. Chromium readings indicate that something harder than it is present, namely silica or alumina (sand). It can also be produced in new engines during the run-in period. Chromium in hydraulic systems is typically from valve spools or cylinder rods. It is also produced by harder abrasives. Chromium is also found in final drive and differential bearings.

Copper is a soft metal from bronze alloys that are present in engines, hydraulic pumps, differentials, final drives and in cooler cores. In engines, its presence could be caused by a coolant core or water pump leak, but also from thrust washers in the camshaft, rocker arm or piston wrist bushings. When present with Glycol (in association with potassium and sodium) it could be coming from oil cooler. When it is associated with lead and/or tin, but without glycol traces, it is an indication that it is coming from the bearings/bushings. New oils can  promote high copper generation during run-in periods, ranging from 10 to 100 parts per million or more. Larger generation of copper is typically triggered by water, silica (dirt), high temperature operation and most importantly, by additive incompatibility from fluid mixing. Copper is also found in final drives equipped with park brakes and slip spin/diff lock differentials, or from thrust washers.

Aluminum is a wear element that generally comes from pistons in engines. High aluminum associated with silica is probably dirt.  If aluminum is found in hydraulic systems, it could generally be assumed it comes from dirt ingestion. Aluminum in final drives can only be dirt or sand. Some bearings can include aluminium (eg refrigeration compressor bearings and some main engine bearings)

Tin is a metal used in soft alloys of bronze in combination with lead. It is generally present in small amounts in hydraulic pumps. However, when tin is present in engines, it is usually associated with lead and copper to indicate bearing wear.

Lead is a very soft metal used in alloys in combination with tin for engine bearings and bushings. Lead is present in hydraulic pump alloys as well. Highly oxidized engine oils attack bearing material, which increases lead readings.

Nickel it is seldom seen in oil analysis but when it shows up it is an indication of turbocharger cam plate wear. 

Titanium is not a typical wear metal present in oil analysis from construction equipment. Some traces are possible from some alloys. Titanium in the form of titanium oxides can be found in oil analyses as a contaminant from operation in bauxite mines.