Exam Questions And Correct Answers

Machinery Lubrication Technician Certification (MLA Level 2) Practice Exam Questions And Correct Answers (Verified Answers) Plus Rationales 2026 Q&A | Instant Download Pdf

• Which of the following is the primary function of lubricants in

machinery?

• Cooling
• Reducing friction
• Cleaning
• Sealing

Rationale:

Lubricants primarily reduce friction between moving parts, minimizing wear and energy loss. 1 / 4

• What is the typical viscosity range for a hydraulic oil used in mobile

equipment?

• 5–10 cSt
• 10–20 cSt
• 15–46 cSt
• 50–100 cSt

Rationale:

Hydraulic oils are selected for appropriate viscosity to ensure proper flow and protection in mobile equipment, typically between 15–46 cSt.

• Which additive is commonly used in lubricants to prevent corrosion?
• Detergents
• Rust inhibitors
• Anti-foam agents
• Viscosity index improvers

Rationale:

Rust inhibitors are added to oils to protect metal surfaces from oxidation and corrosion.

• Which lubricant property measures resistance to flow at high

temperature?

• Flash point
• Pour point
• Viscosity index
• Oxidation stability 2 / 4

Rationale:

Viscosity index indicates how much a lubricant’s viscosity changes with temperature, providing stability under varying operating conditions.

• What is the main purpose of an oil analysis program?
• Determine lubricant color
• Detect wear and contamination early
• Increase lubricant viscosity
• Reduce lubricant cost

Rationale:

Oil analysis helps detect abnormal wear, contamination, and lubricant degradation before failure occurs.

• Which of the following is a sign of bearing fatigue?
• Low oil temperature
• Spalling on the raceway
• High lubricant viscosity
• Reduced flow rate

Rationale:

Spalling or flaking on bearing surfaces indicates fatigue failure, often due to insufficient lubrication or overloading.

• The ASTM D4172 test evaluates which property of lubricants?
• Oxidation stability
• Corrosion protection 3 / 4

• Anti-wear performance
• Pour point

Rationale:

The D4172 test measures the wear protection performance of a lubricant under controlled conditions.

• Which type of lubricant is recommended for high-speed electric

motors?

• Grease with high NLGI grade
• Low-viscosity mineral oil
• Heavy gear oil
• Molybdenum disulfide grease

Rationale:

Low-viscosity mineral oils reduce heat buildup and provide proper film thickness for high-speed electric motors.

9. Water contamination in oil primarily causes:

• Improved lubrication
• Corrosion and reduced film strength
• Increased viscosity
• Higher oxidation stability

Rationale:

Water promotes corrosion, reduces oil film strength, and accelerates additive degradation.

• / 4