Machinery Lubrication Technician
Certification Practice Exam Questions
And Correct Answers (Verified Answers)
Plus Rationales 2026 Q&A Instant
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1. What is the primary purpose of lubrication in machinery?
A) Increase electrical conductivity
B) Reduce friction and wear
C) Increase engine noise
D) Decrease component size
Answer: Reduce friction and wear
Rationale: Lubrication creates a protective film between moving surfaces
to minimize friction, heat, and wear.
2. Which lubricant base type is most commonly used in industrial
applications?
A) Vegetable oil
B) Mineral oil
C) Water-based fluid
D) Alcohol-based fluid
Answer: Mineral oil
Rationale: Mineral oils are widely used due to stability, cost-effectiveness,
and good lubrication properties.
,3. What does viscosity measure?
A) Oil color
B) Resistance to flow
C) Oil acidity
D) Oil contamination
Answer: Resistance to flow
Rationale: Viscosity indicates how easily a lubricant flows at a given
temperature.
4. Which device is used to measure oil viscosity?
A) Tachometer
B) Viscometer
C) Hygrometer
D) Barometer
Answer: Viscometer
Rationale: A viscometer determines a fluid’s resistance to flow.
5. What is the main function of an oil filter?
A) Increase oil pressure
B) Remove contaminants from oil
C) Cool the engine
D) Increase oil volume
Answer: Remove contaminants from oil
Rationale: Oil filters trap dirt, debris, and wear particles to protect
machinery.
6. What is the primary cause of oil oxidation?
A) High temperature and oxygen exposure
B) Low pressure
C) Excess water
D) Excess grease
Answer: High temperature and oxygen exposure
Rationale: Heat and oxygen cause chemical breakdown of oil molecules.
, 7. What does ISO viscosity grade indicate?
A) Oil color
B) Oil density
C) Oil viscosity range
D) Oil brand
Answer: Oil viscosity range
Rationale: ISO VG classifies lubricants based on kinematic viscosity.
8. Which contamination type is most damaging to bearings?
A) Water
B) Solid particles
C) Air bubbles
D) Dye
Answer: Solid particles
Rationale: Abrasive particles cause surface wear and fatigue in bearings.
9. What is cavitation in lubrication systems?
A) Oil overheating
B) Formation and collapse of vapor bubbles
C) Oil thickening
D) Filter blockage
Answer: Formation and collapse of vapor bubbles
Rationale: Cavitation creates shock waves that damage metal surfaces.
10.What is the purpose of an oil sump?
A) Store coolant
B) Store lubricating oil
C) Increase fuel supply
D) Filter air
Answer: Store lubricating oil
Rationale: The sump holds oil for circulation in the lubrication system.
11.Which additive improves oil oxidation resistance?
A) Detergent
B) Antioxidant
Certification Practice Exam Questions
And Correct Answers (Verified Answers)
Plus Rationales 2026 Q&A Instant
Download Pdf
1. What is the primary purpose of lubrication in machinery?
A) Increase electrical conductivity
B) Reduce friction and wear
C) Increase engine noise
D) Decrease component size
Answer: Reduce friction and wear
Rationale: Lubrication creates a protective film between moving surfaces
to minimize friction, heat, and wear.
2. Which lubricant base type is most commonly used in industrial
applications?
A) Vegetable oil
B) Mineral oil
C) Water-based fluid
D) Alcohol-based fluid
Answer: Mineral oil
Rationale: Mineral oils are widely used due to stability, cost-effectiveness,
and good lubrication properties.
,3. What does viscosity measure?
A) Oil color
B) Resistance to flow
C) Oil acidity
D) Oil contamination
Answer: Resistance to flow
Rationale: Viscosity indicates how easily a lubricant flows at a given
temperature.
4. Which device is used to measure oil viscosity?
A) Tachometer
B) Viscometer
C) Hygrometer
D) Barometer
Answer: Viscometer
Rationale: A viscometer determines a fluid’s resistance to flow.
5. What is the main function of an oil filter?
A) Increase oil pressure
B) Remove contaminants from oil
C) Cool the engine
D) Increase oil volume
Answer: Remove contaminants from oil
Rationale: Oil filters trap dirt, debris, and wear particles to protect
machinery.
6. What is the primary cause of oil oxidation?
A) High temperature and oxygen exposure
B) Low pressure
C) Excess water
D) Excess grease
Answer: High temperature and oxygen exposure
Rationale: Heat and oxygen cause chemical breakdown of oil molecules.
, 7. What does ISO viscosity grade indicate?
A) Oil color
B) Oil density
C) Oil viscosity range
D) Oil brand
Answer: Oil viscosity range
Rationale: ISO VG classifies lubricants based on kinematic viscosity.
8. Which contamination type is most damaging to bearings?
A) Water
B) Solid particles
C) Air bubbles
D) Dye
Answer: Solid particles
Rationale: Abrasive particles cause surface wear and fatigue in bearings.
9. What is cavitation in lubrication systems?
A) Oil overheating
B) Formation and collapse of vapor bubbles
C) Oil thickening
D) Filter blockage
Answer: Formation and collapse of vapor bubbles
Rationale: Cavitation creates shock waves that damage metal surfaces.
10.What is the purpose of an oil sump?
A) Store coolant
B) Store lubricating oil
C) Increase fuel supply
D) Filter air
Answer: Store lubricating oil
Rationale: The sump holds oil for circulation in the lubrication system.
11.Which additive improves oil oxidation resistance?
A) Detergent
B) Antioxidant
