Types of Synthetic Oils Complete guide

Synthetic oils

1. Polyalpha-olefin (PAO)
2. Synthetic esters
3. Polyalkylene glycols (PAG)
4. Phosphate esters
5. Alkylated naphthalenes (AN)
6. Silicate esters
7. Ionic fluids

Solid lubricants

PTFE: polytetrafluoroethylene (PTFE) is typically used as a coating layer on, for example, cooking utensils to provide a non-stick surface. Its usable temperature range up to 350 °C and chemical inertness make it a useful additive in special greases. Under extreme pressures, PTFE powder or solids is of little value as it is soft and flows away from the area of contact. Ceramic or metal or alloy lubricants must be used then. "Teflon®" is a brand of PTFE owned by DuPont Co.

Inorganic solids: Graphite, hexagonal boron nitride, molybdenum disulfide and tungsten disulfide are examples of materials that can be used as solid lubricants, often to very high temperature. The use of some such materials is sometimes restricted by their poor resistance to oxidation (e.g., molybdenum disulfide can only be used up to 350°C in air, but 1100°C in reducing environments).

Metal/alloy: Metal alloys, composites and pure metals can be used as grease additives or the sole constituents of sliding surfaces and bearings. Cadmium and Gold are used for plating surfaces which gives them good corrosion resistance and sliding properties, Lead, Tin, Zinc alloys and various Bronze alloys are used as sliding bearings, or their powder can be used to lubricate sliding surfaces alone, or as additives to

Aqueous lubrication

Aqueous lubrication is of interest in a number of technological applications. Strongly hydrated brush polymers such as PEG can act as lubricants at liquid solid interfaces. By continuous rapid exchange of bound water with other free water molecules, these polymer films keep the surfaces separated while maintaining a high fluidity at the brush–brush interface at high compressions, thus leading to a very low coefficient of friction.

Other relevant phenomena

'Glaze' formation (high temperature wear)

A further phenomenon that has undergone investigation in relation to high temperature wear prevention and lubrication, is that of a compacted oxide layer glaze formation. This is the generation of a compacted oxide layer which sinters together to form a crystalline 'glaze' (not the amorphous layer seen in pottery) generally at high temperatures, from metallic surfaces sliding against each other (or a metallic surface against a ceramic surface). Due to the elimination of metallic contact and adhesion by the generation of oxide, friction and wear is reduced. Effectively, such a surface is self-lubricating.

As the 'glaze' is already an oxide, it can survive to very high temperatures in air or oxidising environments. However, it is disadvantaged by it being necessary for the base metal (or ceramic) having to undergo some wear first to generate sufficient oxide debris.

 Additives

A large number of additives are used to impart performance characteristics to the lubricants. The main families of additives are:

• Antioxidants
• Detergents
• Anti-wear
• Metal deactivators
• Corrosion inhibitors, Rust inhibitors
• Friction modifiers
• Extreme Pressure
• Anti-foaming agents
• Viscosity index improvers
• Demulsifying/Emulsifying
• Stickiness improver, provide adhesive property towards tool surface (in metalworking)
• Complexing agent (in case of greases)

Note that many of the basic chemical compounds used as detergents (example: calcium sulfonate) serve the purpose of the first seven items in the list as well. Usually it is not economically or technically feasible to use a single do-it-all additive compound. Oils for hypoid gear lubrication will contain high content of EP additives. Grease lubricants may contain large amount of solid particle friction modifiers, such as graphite, molybdenum sulfide.

Application by fluid types

1. Automotive
1. Engine oils
1. Petrol (Gasoline) engine oils
2. Diesel engine oils
2. Automatic transmission fluid
3. Gearbox fluids
4. Brake fluids
5. Hydraulic fluids
2. Tractor (one lubricant for all systems)
1. Universal Tractor Transmission Oil – UTTO
2. Super Tractor Oil Universal – STOU – includes engine
3. Other motors
1. 2-stroke engine oils
4. Industrial
1. Hydraulic oils
2. Air compressor oils
3. Gas Compressor oils
4. Gear oils
5. Bearing and circulating system oils
6. Refrigerator compressor oils
7. Steam and gas turbine oils
5. Aviation
1. Gas turbine engine oils
2. Piston engine oils
6. Marine
1. Crosshead cylinder oils
2. Crosshead Crankcase oils
3. Trunk piston engine oils
4. Stern tube lubricants