What is a lubricant?
A Lubricant can be anything, which controls the friction forces between two surfaces. A lubricant, depending upon the necessity and design can, either reduce or increase or control the friction. It is also used as a sealing medium, cooling medium and cleansing medium, depending upon applications and design.

A lubricant can be liquid, semi-liquid or solid. Grease falls under the semi-liquid category. Solid lubricants can be made mostly of plastics, especially PVC and Teflon. Normally, a lubricant means liquid lubricant.

How is lubricant made?
A lubricant is made in a blending plant. In a blending plant, the base oils (which may constitute up to 99% of the lubricant, by volume) are mixed with specially selected additives. Before blending, the base oils are mixed etc. Blending is normally done in Kettles, where the oil is heated up to 60ºC and heavily agitated.

Either mechanical or pneumatic agitation can be used. Additives are then added and the whole mixture homogenised by thorough mixing - technically called blending. This is not a process whereby the chemical characteristics change - there is molecular change. After blending, the product is filtered and then packed. In special cases - like Transformer Oil - the product is degassed and thoroughly filtered.

The newer form of blending- especially used in large blending plants, is in-line blending, where the different components mix while flowing inside a pipeline.

What are two main constituents of a lubricant?
The two main constituents of a lubricant are base oils and additives. Base oils can be more than one (depending upon the final product viscosity needed) and additives can either be a mixture (called an additive package) or components.

What is a base oil?
Base Oil is the name given to basic building block of a lubricant. It is sometimes also called base stocks. Base stocks are mineral (or petroleum) or synthetic origin, although vegetable stocks may be used for specialized applications. The base stock provides the basic lubricating requirements of a lubricant.

However, unless it is supported with additives, base oil will degrade and deteriorate very rapidly in some operating conditions. Depending upon the base stock, petroleum, synthetic or others, different additive chemistries need to be used for making different kinds of lubricant.

Who supplies base oil?
Base oils are made and supplied by refineries. A refinery is a plant where the crude oil is distilled into various fractions. Normally the last but one portion of the heaviest stocks is the lubricant base stock. The main base oil producers are the big oil companies.

How are base oil made?
Base oils are made in the refinery by a number of processes - basically distillation. Distillation under atmospheric pressure removes the gasoline and distillate fuel components, leaving a "long residue" containing the lube oil and the ashpalt. Further distillation under vaccum yields "neutral distillates" overhead and an ashpalt residue. Simple treatment with sulphuric acid, line and clay turns the distillate into acceptable LVI stocks.

For HVI and MVI stocks, some form of solvent extraction is necessary to remove colored, unstable and low VI components. Finally, wax is removed by dissolving the oil into methyl-ethyl ketone (MEK) and chilling and filtering to yield oils with pour points in the -10 to -20ºC range. At the refiner's option, the oils may be "finished" with hydrogen to remove sulphur, nitrogen and color bodies.

What are the different kinds of base oil?
Base oils, as discussed earlier, are classified, and traded mainly according to their viscosities. The main base oils that are commonly used in the lubricating oil industry are 70N, 150N, 500N, and 150 Bright Stock. These oils vary in color and viscosity - the color getting darker and the viscosity increasing as we go from 70N to 150BS.

As shown above, the number of all neutrals indicates the viscosity of the product at 40ºC in the old unit of Saybolt Universal Seconds. For Bright stock, the number indicates the SSU viscosity at 100oC.

What kind of base oil are used for what kind of applications?
Napthenic base oils are used when the final lubricant is expected to work at moderately lower temperatures. Paraffinic base oils are used when the Viscosity Index requirement is high and the temperatures are not that much lower. These are the largest kind of lubricating base stocks used. Aromatic base oils are seldom used - and find their main application as processing oil.

Extra Solvent treated paraffinic and naphthenic base oils are used to make turbine oils. XHVI base oils, with very low volatility, are used to make thinner oils for the extreme cold weather. Synthetic base oils are used in applications where the temperature is either too high or too low.

Why are these base oil sometimes called as mineral oils?
Base oils are called mineral base oils because they are obtained from the mineral-deteriorated-crude oil. This is to differentiate them from the "synthetic" base stocks.

What other kinds of base oil are available in the world?
The other kinds of base fluids used to make lubricants are Olefin Oligomers (PAOs) Dibasic Acid Esters, Polyolesters, Alkylated aromatics, Polyalkylene glycols, phosphate esters and vegetable oils like Rape seed oil.

Why are base oil called synthetic?
They are called synthetic because their molecules are created rather than the naturally available one of the petroleum based mineral base oils. For example: Poly Alpha Olefin is synthesised in the laboratory by combining small molecules of a chemical called Decene.

What are the main advantages of synthetic base oil over mineral base oil?
The main advantages of the synthetic oils are in their high viscosity indexes, higher flash points, lower pour points and very low volatility (tendency to evaporate at higher temperatures). This makes them valuable blending components when compounding for extreme service at both high and low temperatures.

What are the main disadvantages of synthetic base oil over mineral base oil?
The main disadvantage of synthetic lubricants is that they are inherently more expensive than mineral oils, and are limited in supply. This limits their use to specialty oils and greases that command premium prices. Esters suffer further disadvantage of greater seal-swelling tendencies than hydrocarbons: so, caution has to be exercised in using them in applications where they may contact elastomers designed for use with mineral oils.

Where are these synthetic base oil used?
Synthetic base oils are used to make specialized lubricants for use in extreme conditions. For example: To make Gulf Formula G which is 5W40 viscosity grade lubricant, it is a necessity to use synthetic base stocks, because normal mineral based lubricants cannot work at the lower temperatures at which Formula G is expected to work. Another mandatory application of synthetic fluids is the Fire Resistant Hydraulic Fluid.

What are hydrofinished base stocks?
Hydrofinishing is a process by which the base oil is treated with hydrogen, usually following the conventional solvent refining to saturate olefins. Results in improved color, demulsibility and foam characteristics. This is different from the hydrocracking process.

What is viscosity?
Viscosity is a measure of a fluid's resistance to flow. For lubricating oil in general, viscosity is the most important controlling property. In a bearing that is operating properly with a fluid film between its surfaces, the viscosity of the oil at the operating temperature is the property which determines the bearing friction, heat generation and the rate of oil flow through the bearing under given conditions of load, speed and bearing design.

The oil should have a viscosity at the operating temperature that is correct for maintaining a fluid film between the bearing surfaces, despite the pressure tending to squeeze it out. While a reasonable factor of safety is usually desirable, excessive viscosity should be avoided because of unnecessary friction and heat generation.

Viscosity is also useful for identification of grades of oil and for following the performance of oils in service. An increase in viscosity usually indicates that the oil has deteriorated to some extent, a decrease ordinarily indicates dilution. The permissible extent of viscosity increase before corrective measures are taken is largely a matter of experience and judgment of the operator.

What is a Flash point of a petroleum product?
The Flash point of a petroleum product is the temperature at which enough vapour is produced so that air-vapour mixture will flash in the presence of a small flame. From the view point of safety, flash points are of most significance at or slightly above the maximum temperature that may be encountered in storage, transportation, and use of liquid petroleum products, either enclosed or open containers.

In this temperature range, the relative fire and explosion hazard can be estimated from the flash point. For products with flashpoints below 100ºF, special precautions are necessary for safe handling. Flash point is also used by manufacturers and marketers of petroleum products to detect contamination.

A substantially lower flash point than expected for the product is a reliable indicator that a product has become contaminated with a more volatile product such as gasoline. The flash point is also an aid in establishing the identity of a particular petroleum product.

What is the Pour Point of a Petroleum product?
The pour point of petroleum product is the minimum temperature at which the fluid will pour or flow under test conditions. This is an indicator of the ability of an oil or distillate fuel to flow at cold operating temperatures. The pour point of a product is often mistakenly taken as coldest ambient temperature at which equipment using the product as fuel or lubricant can be operated.

The product in question may have a Cloud Point 10 to 20ºF above the pour Point and this may become the limiting temperature. (At cloud Point, the wax crystals in the oil start forming in the product, the wax crystals tend to clog filter screens in fuel and lubricant circulation systems, preventing proper equipment operation)

This problem can occur in situations where a product has been artificially lowered by means of an additive (Pour Point Depressant) the additive does not lower the Cloud Point. There are other reasons for setting a minimum operating temperature well above a product's Pour Point especially with lube oils.

The viscosity may become so high at the pour point that large amounts of power are wasted overcoming the high fluid friction. Insufficient lubricant flow to location where needed is another consideration.

Why are additives used in lubricating oil?
Additives are used in lubricating oil to change or alter or enhance its properties. Base oil as such cannot be used in most of the present-day lubricating applications. Their properties - like resistance to heat, oxygen, wear etc - have to be increased. This increment is done with the use of these additives. To increase the resistance to oxidation, we add 'antioxidants', to increase resistance to wear, we add 'anti-wear additives'

What do additives do? How do they work?
Oxidation Inhibitor Prevents varnish and sludge formation on bearings or in circulating systems. Retards aging of the oil. Lengthens service and storage life of oil.

Protects oil itself directly (indirect protects metal parts - varnish and acids) Reacts more readily with oxygen (from air) than does the oil itself, thereby retarding oxidation of the oil. Rust Inhibitor Prevents rusting of ferrous (iron or steel) machine parts Forms a film on ferrous metallic parts thus protecting them from attack by water or other destructive material.

Corrosion Inhibitor Prevents corrosive attack on non-ferrous metallic surfaces Forms a film on non-ferrous metallic parts thus protecting these parts from attack by contaminants in the oil. Detergent Prevents oxidation products (sludge) which have formed in oil from sticking to metal components.

May also remove deposits already formed on metallic components. Usually combined with dispersant additive by chemical reaction, oxidation products (sludge) remain soluble in the oil and do not stick to the metal surfaces.

Which lubricants contain additives?
Almost all lubricating oils used today, with the exception of some quenching oils and some low quality hydraulic oils, contain additives.

Where are these additives made?
The additives are made in special additive processing plants, not in refineries. They are not naturally occurring substances.

How are these additives added to the oil?
Additives are added to the lubricating base stock in the blending kettle. The oil is normally heated to around 50 to 60 oC, before addition of the additives. Then the mixture is thoroughly churned and mixed for about 2-3 hours. This makes sure that the additives have dispersed fully in the base oil. The additive can be either pumped into the kettle or, for smaller quantities, manually added to the kettle.

Are synthetic oils better than conventional motor oils?
Synthetic oils are man made lubricants which were originally created for jet aircraft engines. They have a wide range of performance and can protect the engine at very high oil temperature conditions. In other words, they have exceptional thermal stability. Where conventional oils would turn to jelly at very low temperatures and could break down at very high temperature, synthetic lubricants manage to remain fluid at these temperatures and give adequate lubrication where it is needed most.

Does using the right motor oil have anything to do with engine life?
The single most important thing you can do to get long life from your engine is to change your engine oil and oil filter as often as recommended by your car manual. Motor oil that properly lubricates the engine system during the initial part of life can become thick towards the later stages of its sump life. It then cannot flow as required and also blocks the oil filter. This may cause engine damage and seizure in extreme cases.

What does the specification API stand for?
API stands for American Petroleum Institute, a body which specifies the standards that high Quality oils must meet. In most typical passenger car motor oils, the letters API are followed by a se t of two letters such as SJ, SH etc. These standard levels have evolved through the years in response to the changing passenger car engine technology which imposes certain conditions on the quality that most run in it.

The highest API for PCMO's today is API-SJ.

What are the Corresponding Standards of Diesel Engine Oils (DEO's)?
Diesel Engine Oils have an API standard with the letter 'C' such as CF, CG etc. The current highest DEO standard is CG4 meant for use in high speed modern four stroke engines. However DEO's are popularly classified under the MIL (US military) standards. Popular specifications are MIL-B, MIL-C

What is SAE grade?
SAE stands for the Society of Automotive Engineers. The SAE grade specifies the most important parameter for engine oil mainly its viscosity. In other words it tells you the "thickness" of the oil. The lower the number, the "thinner" the oil

When an oil has a rating of 15W40, for example, what does the 'W' stand for?
'W' signifies the winter rating of the oil, showing that it will perform well in cold weather. The lower the number prefixing the 'W', the cooler is the temperature oil can withstand. However, oil with winter rating can still be used on a hot season.

What is multigrade oil?
Multigrade oil carries 2 ratings - a winter and a summer rating. A greater difference between these figures indicates a broader range of operating temperatures.

Multi-viscosity grades or multigrades as they are popularly known are oils which are suitable for use over a wide temperature range. Although winter is not experienced in the Philippines, multigrade oil is still preferred because of its performance and compatibility to modern machines.

How do I choose the best multigrade for my car?
The right SAE rating for oil is shown in your car manual. The most widely used grade in the UK currently is 10W40, but be sure to use the viscosity grade recommended for your car.

Do synthetic oils have a better drain period?
Synthetic oils may sometimes give a longer drain period than conventional motor oils, but this depends more on the engine technology, so do follow the manufacturer's recommendation, rather than the drain period