CLS Cheat Sheet 2026

The 30 highest-yield CLS facts, distilled from real exam questions. Print it, save it as a PDF, or study it here — free, no sign-up.

1. In a tribology study, what does the 'coefficient of friction (COF)' data directly measure? → The ratio of frictional force to normal load between sliding surfaces
2. What is the storage time limit for hazardous waste at a Small Quantity Generator (SQG) facility before the waste must be sent to a permitted facility? → 180 days
3. How should an CLS professional approach a novel situation not covered by standard procedures? → Apply foundational principles, assess risks, consult resources, and document decisions
4. Which emerging sensor technology can measure oil viscosity, density, and dielectric constant simultaneously in real time without removing a sample? → MEMS (micro-electromechanical systems) in-line fluid sensors
5. Which type of surface fatigue wear produces shallow, saucer-shaped pits on gear tooth flanks or rolling element bearing raceways? → Pitting
6. A lubrication professional is asked to evaluate two lubricants for the same application. The most rigorous professional approach is to: → Review technical data sheets, conduct lab analysis, and pilot test before full adoption
7. How do CLS professionals evaluate the quality of research evidence? → By assessing methodology, sample size, peer review, and relevance
8. Which sampling practice introduces the highest risk of a non-representative oil sample that could undermine QC decisions? → Sampling immediately after an oil change without running the equipment
9. What is the primary purpose of a Weibull analysis in lubrication engineering research? → To statistically model bearing or component failure probability over time
10. What role does mentorship play in Certified Lubrication Specialist professional development? → It provides guided learning from experienced practitioners to develop practical skills
11. Which type of study design allows a CLS to infer causation rather than mere correlation between a lubrication change and equipment outcome? → Controlled prospective experiment
12. A lubrication specialist discovers a used oil storage tank is leaking onto soil. Under CERCLA, who may be held liable for cleanup costs? → Any potentially responsible party including current owners, past owners, and generators
13. Which factor most significantly increases the re-lubrication interval for a grease-lubricated bearing? → Reducing operating temperature and speed
14. Patch test colorimetry in used oil analysis is primarily used to evaluate which property? → Varnish potential and deposit-forming tendency
15. A facility tracks lubrication-related Work Order closure rates as a KPI. Which trend should trigger a process improvement review? → Closure rate declining over three consecutive months
16. Which regulation requires lubricant suppliers to provide a Safety Data Sheet (SDS) to downstream users before or at the time of first product delivery? → OSHA HazCom Standard 29 CFR 1910.1200
17. When consolidating lubricants in a plant, what is the primary goal of a lubricant rationalization program? → Reduce the number of lubricant products without compromising equipment protection
18. When assessing fire risk in a system that uses fire-resistant hydraulic fluids (FRHF), which fluid type offers the HIGHEST level of fire resistance? → Phosphate ester synthetics (HFDR)
19. What are potential consequences of regulatory non-compliance for Certified Lubrication Specialist professionals? → Fines, license revocation, legal liability, and reputational damage
20. What is the primary value of case analysis in Certified Lubrication Specialist professional development? → Developing critical thinking by applying theory to realistic scenarios
21. A gear oil is labeled 'ISO VG 220.' What does the '220' represent? → The oil's kinematic viscosity in cSt at 40°C, midpoint of a defined range
22. Which additive is primarily responsible for preventing rust in water-contaminated circulating oil systems? → Sodium sulfonate rust inhibitor
23. How should CLS professionals evaluate new technology tools? → Assess functionality, reliability, security, and alignment with professional needs
24. What is the primary purpose of a centralized lubrication system in industrial equipment? → To deliver precise lubricant quantities to multiple points automatically
25. What is the primary function of a thickener in lubricating grease? → To act as a sponge-like structure that holds the base oil
26. When a lubrication specialist discovers that a recommended lubricant is unavailable, what is the most professional first step? → Consult the OEM manual and identify an approved equivalent
27. A technician notices a white, milky appearance in the sight glass of a gearbox. What does this MOST likely indicate? → Water contamination emulsified in the oil
28. Which approach best demonstrates professional competency in CLS practice? → Integrating education, experience, and evidence-based decision making
29. How can improper lubricant selection affect machine performance? → It increases the risk of overheating and damage
30. A used oil sample shows a significant drop in viscosity compared to the baseline. Which contamination is most likely responsible? → Fuel dilution