CLS CLS Oil Analysis & Condition Monitoring 2 — Questions and Answers
Question 1: Which oil analysis parameter is the best early indicator of coolant ingress into an engine lubricant?
- Elevated sodium and potassium levels (Correct answer)
- Increased silicon content
- Higher copper concentration
- Rising iron levels
Correct answer: Elevated sodium and potassium levels
Coolant contains ethylene glycol stabilized with sodium and potassium additives, which appear in oil analysis when a seal fails.
Question 2: What is the primary purpose of establishing an oil analysis baseline for a new machine?
- To set reference values for detecting future abnormal changes (Correct answer)
- To verify the machine is warrantied
- To measure the machine's production output
- To confirm the lubricant meets OEM specifications
Correct answer: To set reference values for detecting future abnormal changes
Baseline samples capture the 'normal' oil condition so future results can be trended and anomalies detected early.
Question 3: Patch test colorimetry in used oil analysis is primarily used to evaluate which property?
- Varnish potential and deposit-forming tendency (Correct answer)
- Viscosity at high temperature
- Wear metal concentration
- Water content by volume
Correct answer: Varnish potential and deposit-forming tendency
The membrane patch colorimetry (MPC) test quantifies insoluble oxidation by-products that indicate varnish formation risk.
Question 4: Elevated silicon levels found during routine oil analysis most often point to which contamination source?
- Airborne dust and dirt ingression (Correct answer)
- Wear of bearing surfaces
- Fuel dilution
- Coolant leak
Correct answer: Airborne dust and dirt ingression
Silicon is a primary element in silica (sand and dust), making elevated silicon a classic indicator of inadequate air filtration.
Question 5: According to ASTM D445, kinematic viscosity of a lubricant is measured at which two standard temperatures?
- 40°C and 100°C (Correct answer)
- 25°C and 80°C
- 20°C and 60°C
- 50°C and 120°C
Correct answer: 40°C and 100°C
ASTM D445 standardizes kinematic viscosity measurement at 40°C (operational reference) and 100°C (high-temperature reference).
Question 6: A used oil sample shows a significant drop in viscosity compared to the baseline. Which contamination is most likely responsible?
- Fuel dilution (Correct answer)
- Soot accumulation
- Oxidation
- Water contamination
Correct answer: Fuel dilution
Unburned fuel is a light hydrocarbon that mixes with engine oil and reduces its viscosity, thinning the protective film.
CLS CLS Oil Analysis & Condition Monitoring 2
Which oil analysis parameter is the best early indicator of coolant ingress into an engine lubricant?