ASE G1 Auto Maintenance and Light RepairEngine SystemsHard
A technician is performing a routine oil change. After draining the oil, they notice a significant amount of shiny, non-magnetic metallic particles in the old oil. What does this MOST likely indicate?
- ABearing wear
- BNormal wear and tear
- CContamination from fuel dilution
- DCarbon buildup
Show answer & explanationAnswer & explanation
Correct answer: A. Bearing wear
Shiny, non-magnetic metallic particles in engine oil are typically aluminum or copper/brass, which are common materials for engine bearings (main, rod, cam). Their presence indicates wear in these critical components, which use a non-ferrous outer layer. Magnetic particles would suggest steel wear (e.g., from gears or camshafts).
Why the other options are wrong
- B. While some microscopic particles are normal, a 'significant amount' of visible metallic particles indicates abnormal wear.
- C. Fuel dilution would thin the oil and smell of fuel, but would not introduce metallic particles.
- D. Carbon buildup would appear as black, gritty particles, not shiny metallic ones.
Metallic Particles in Oil
The presence of visible metal fragments in used engine oil, indicating abnormal wear of internal engine components.
- Shiny, non-magnetic particles often indicate bearing wear (aluminum, copper/bronze).
- Dark, magnetic particles suggest ferrous metal wear (steel, iron from gears, camshafts).
- Requires further investigation to prevent catastrophic engine failure.
Memory trick: 'SHINY' and 'NON-MAG' means 'BEARING' trouble is 'DRAGGING'.