where do these elements come from:
Iron: Comes from cylinder liner, camshaft, oil pump, and timing chain wear
Chromium: Comes from piston ring wear
Copper: Comes from bearings, valve guides, and bushings wear
Lead: Comes from bearing wear
Aluminum: Comes from piston and piston thrust bearing wear
Silver & Tin: Comes from bearing wear
Silicon: dirt ingestion, sometimes used as an anti-foamant
Molybdenum: anti-wear additive and friction reducer
Boron: anti-wear additive and friction reducer
Calcium: common additive with many functions, primarily a detergent
Magnesium: common additive with many functions
Phosphorous: anti-wear additive and friction reducer, shear stabilizer
Zinc: anti-wear additive and friction reducer, shear stabilizer
Link to this massive write up