Answers:

1. Grease is a semi-solid, consisting of a soap dispersed throughout a liquid lubricating oil. The liquid lubricant maybe a petroleum oil or even a synthetic oil and it may contain any of the additives for specific requirements.
2. Grease have higher shear or frictional resistance than oils and therefore, can support much heavier loads at lower speeds.
3. They also do not require as much attention unlike the lubricating liquids.
4. Greases have a tendency to separate into oil and soap
5. Greases are used in situation where:
   • Oil cannot remain in place, due to high load, low speed, intermittent operation, sudden jerks etc.
     For e.g. rail axle boxes
   • in bearings and gears that work at high temperatures
   • where bearings needs to be sealed against entry of dust, dirt, grit or moisture, because greases are less liable to contamination by these
   • In situations where dripping or spurting of oil is undesirable, because unlike oil, greases if used do not splash or drip over articles being prepared by the machine
     For e.g.: in machines preparing paper, textiles, edible articles etc.