---
title: "Lubricants and applications of types"
subject: "Engineering Chemistry"
chapter: 8
key: "semester_2/engineering_chemistry:lubricants-types-application"
source: https://www.bctengineer.com/q/semester_2/engineering_chemistry/lubricants-types-application
site: BCT Engineering
---

# Lubricants and applications of types

Engineering Chemistry · Chapter 8: Lubricants and Paints

- Asked in: 2071 Bhadra, 1+2 marks
- Video: [Lubricants || Lubricant Important Functions And Classification ||Lubrication ||Engineering Chemistry](https://www.youtube.com/watch?v=Kuj2X6ncPBc) — Chemistry by Dr. Anjali Ssaxena
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_2/engineering_chemistry/lubricants-types-application
- Whole chapter: https://www.bctengineer.com/md/semester_2/engineering_chemistry/chapter-8

## Question

What is lubricant? Write about the application of different types of lubricants.

## Short answer

A lubricant reduces friction and wear. Thin mineral oils are used in watches and instruments, medium oils in engines, thick oils in heavy machines. Greases serve bearings, chassis and open gears where oil cannot stay. Solid lubricants like graphite and MoS₂ are used at high temperature, in vacuum, or where contamination must be avoided.

## Answer

A **lubricant** is a substance introduced between two moving or sliding surfaces to reduce friction and wear between them.

#### Applications of the types
- **Liquid lubricants (oils):** thin mineral oils in watches, sewing machines and instruments; medium oils in engines, gearboxes and turbines; thick oils in heavy machines. Vegetable oils in food machinery; synthetic oils at extreme temperatures.
- **Greases:** in bearings, chassis, axles and open gears where oil cannot stay, at heavy load and slow speed.
- **Solid lubricants:** graphite and MoS₂ at high temperature, in vacuum, and where oil would contaminate, such as in food and textile machines.

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. Which lubricant is suitable for watches, sewing machines and instruments?
   A. Thick oil
   B. Graphite
   C. Thin mineral oil
   D. Calcium grease
   Answer: C. Thin mineral oils are used in light, fast, delicate machinery. (Key point: Thin oils)

2. Where are greases preferred to oil?
   A. Where oil cannot stay, e.g. bearings, chassis and axles at heavy load and slow speed
   B. Inside high-speed engines needing cooling
   C. In vacuum at very high temperature
   D. In watches
   Answer: A. Greases stay in place, so they suit bearings, axles and open gears. (Key point: Grease use)

3. When are solid lubricants used?
   A. For light delicate instruments
   B. Only in car engines
   C. At high temperature, in vacuum, or where oil would contaminate
   D. When a cooling fluid is required
   Answer: C. Graphite and MoS2 are used when oils fail or contaminate. (Key point: Solid use)

## Related in Engineering Chemistry

- [Lubricant functions; solid lubricants](https://www.bctengineer.com/question.md?key=semester_2%2Fengineering_chemistry%3Alubricant-functions-solid) — Engineering Chemistry, chapter 8
- [Lubricant functions and paint [partly illegible]](https://www.bctengineer.com/question.md?key=semester_2%2Fengineering_chemistry%3Alubricant-paint-partial) — Engineering Chemistry, chapter 8
- [Lubricant functions; grease and solid lubricant use](https://www.bctengineer.com/question.md?key=semester_2%2Fengineering_chemistry%3Alubricant-functions-grease-solid) — Engineering Chemistry, chapter 8

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