Liquid lubricants are classified on basis of original origin as
Vegetable oil: these are obtained from plants.
E.g. olive oil, palm oil, cottonseed oil etc
Animal oil: these are obtained from animals like fishes etc.
Mineral oil: These are obtained from petroleum oils containing mostly of hydrocarbons
Blended oil: These are mineral oils mixed with vegetable or animals oils and various additives to improve its lubricating property.
Synthetic oils: These are designed for acid esters, organic phosphate esters, halogenated hydrocarbons, poly alkaline glycols and their derivatives