Which Lubricant?

In Roman times the first 'greases' were animal fats used to lubricate the wheels of their chariots, so this idea has been around a while. 

In simple terms a grease is a thickened oil, the thickener is there to act as a sponge and hold the oil in place. Under pressure the 'sponge' releases the oil film to lubricate the contacts.
Oils come in many different types both mineral and synthetic with different properties depending upon their chemical make up. In a lubrication application the oil creates a sacrificial layer or film which shears and isolates the moving surfaces. Within oils many different additives can be used to enhance their properties including their viscosity, viscosity index, oxidation resistance and corrosion protection.

Greases are very simply a thickened oil. The thickener is like a sponge and holds the oil in a matrix which under pressure releases the oil to lubricate the surfaces. A grease can be based upon a mineral or synthetic oil, thickened with a metallic soap or sometimes an absorbent particle, clay, silica or PTFE and additives can be either within the base oil or also held within the matrix. Solid additives are also sometimes included to reinforce the boundary lubrication properties of the material under extreme pressure.

A Dry Film Lubricant is either a solid lubricant that is added to a coating which is bonded to the surface like a ‘low friction paint’ or a layer of un-bonded solid lubricant is applied between surfaces to act as a sacrificial layer or film.Aerosol or spray lubricants are simply one of the above oils, greases or dry film lubricants (or a mixture in some cases), suspended in a carrier  fluid or solvent and with the addition of a propellant to push it out of the can.  Depending upon the nozzle and pressure sometimes the product is a fine atomised mist and sometimes it is a stream of fluid.

which lubricant oil greases dryfilm