Motor oil is chosen with suitable viscosity so that:

  1. it becomes a solid
  2. it boils easily
  3. it flows when cold and still lubricates when hot
  4. it never flows
Answer

C) it flows when cold and still lubricates when hot

Viscosity changes with temperature. SLO P-11-B-41 · Understanding

Physics MCQ · More Fluid Statics and Dynamics MCQs · Practise