A high aluminum count in a spectrographic oil test most likely indicates wear of which engine component?

• A. Cylinder wear
• B. Piston wear
• C. Crankshaft bearing wear
• D. Oil pump wear

Answer: (B)

Aluminum in the oil points to wear from components made with aluminum alloys. In most engines, the piston is an aluminum alloy part, and when the piston wears—especially the piston skirt area or the ring grooves—tiny aluminum particles get into the lubrication system. A spectrographic oil test detects these metal fragments, so a high aluminum reading is a strong indicator that piston wear is occurring. Other engine parts that wear—like crankshaft bearings or the oil pump—are made from different metals (such as iron, copper, tin, or steel), so they wouldn’t typically produce a spike in aluminum alone.