Features:
» Acid-Clay Process for used oil recycling/reprocessing is Old and popular. This is a  
    Proven technology worked for many years worldwide. Can be
    set-up for  very small capacity.
» Low Capital investment. Makes it most cost effective for small and tiny scale plants.
» Non sophisticated, Very simple process. Simple to operate, No advanced instruments, No    skilled operators required.

Drawbacks:
» Causes Environmental pollution due to generation of acid sludge and acid gas emission.    Disposal of acid sludge is a problem.
» Causes corrosion of equipments reducing its life.
» Gives Lower yield. Due to loss of oil in sludge as well as clay since higher dosage of clay is    required.
» As most of the government has adopted stringent pollution control regulations, this process    is on its  way out.

Features
» No acid is required.
» It is simple process
» Suitable for small capacity plant.

Drawbacks:
» Very high clay consumption, low yield, inconsistent quality.
» Disposal of large quantity of spent clay is a environmental problem.
» Suitable only for very small capacity plants.
» Process is dependent on a particular type of clay which may not be available from all the    sources.

Features:
» Suitable for high capacity plants.
» Thin film evaporator is capable of Operating at high vacuum and normally used for high     value and heat     sensitive products.
» Does not cause pollution.
» Sophisticated Equipments & Process
» Produces good quality Base Oils.

Drawbacks:
» Operates at high temperature & very high Vacuum. Require special /expensive thermic    fluids & heating     system. High cost of heating fluid and High operational costs.
» Requires high capital investment.
» Plant has to be of a higher capacity to make it economically viable.
» Require highly skilled & Operational maintenance Staff. As it has very sophisticated    equipments.
» Higher Fuel Cost.
» Due to multiple stage of distillation involving heating & cooling.

Features:
» Simple pipe furnace, convection heating at low heat flux by re-circulating flue gases.
» No moving part on process side.
» No prior removal of gas oil is required.
» Simple instrumentation.

Features:
» In this process propane is used as solvent to remove bitumen, additives, metals and tar etc.
» Solvent is recyclable.
» Does not cause pollution.
» Produce Good quality Base Oils.

Drawbacks:
» Has to operate at higher pressure ( 10 atm. ) at ambient temperature ( 27oC ) require high    pressure sealing systems. (making system expensive and complicated)
» Involves operational solvent losses and highly skilled operating and maintenance    personnel and system is required.
» Economical only for high capacity plants.
» Propane being very hazardous, Fire & explosion hazard is associated with this process.