What is a modern lubricant?
A lubricant is the material that lies between two surfaces that are moving with respect to each other. The presence of a lubricant affects the friction between the two surfaces. It is usually used to reduce friction, thereby reducing heat and wear, but it is also often used to cool, clean and protect the surfaces from corrosive chemical attack.
A lubricant can be liquid, solid or even a gas. Greases are liquids that have been thickened by the addition of chemical or solid materials. Teflon® and graphite are examples of solid lubricants.
A lubricant is made in a blending plant. There, the base oils (which may constitute up to 99% of the lubricant, by volume) are mixed together with specially selected additives. Before blending, the base oil is purified by filtration and removal of water; after blending the finished product is subjected to quality control checks in the plant´s laboratory before being approved for packing and dispatch.
What does a lubricant do?
Any vehicle owner knows that lubricants are vital to the correct operation of your engine :
• cooling engine hot spots and moving parts
• ensuring that engine parts remain clean
• ensuring leak tightness between engine parts
• cooling engine hot spots and moving parts
Additives bring their help, with the detergent and dispersant additives, and the additives against corrosion.
Base Oil (sometimes also called base stock) is the name given to the main liquid component (or components) of a lubricant. It is. Base oils are mineral (or petroleum) or synthetic in origin, although vegetable oil-derived stocks may be used for specialized applications. The base stock provides the basic lubricating requirements of a lubricant.; i.e. the "oiliness"
However, in most modern lubricants a base oil mixture alone is insufficient to deliver the technical performance characteristics required and to keep the product from rapid degradation in use. Therefore the lubricant manufacturer will mix the base oils with a variety of different additives, each chosen to impart additional performance benefits to the finished oil.
What are the different kinds of base oils?
Base oils are be classified by both viscosity and their generic chemical composition, itself a function of the original crude oil and/or the refining process. Depending on the proportions of hydrocarbon molecule type: base oils can be either paraffinic, naphthenic or aromatic in nature. There are several widely used viscosity classifications, of which the term ‘solvent neutral´ is the most common, e.g. SN 150 and SN 500, where the number represents the SUS viscosity (measured in Say bolt Universal Seconds at 40 C). Base oils are also classified by their viscosity index (a calculated figure based on the viscosities measured at both 40 and 100 C). Thus oils are either Low Viscosity Index (LVIs) or Medium Viscosity Index (MVIs), High Viscosity Index (HVIs) or extra High Viscosity Index (XHVIs). The higher the viscosity index, the less the oil will ‘thin down´ upon heating, and the less it will ‘thicken up´ upon cooling.
Base oils are also be defined by the type of refining process used: solvent extraction (for solvent neutral oils) is widely used, but more highly refined oils can be made by a hydro-finishing process or by hydro-cracking.
Why are some oils called "synthetic" and others "mineral" ?
This refers to the origin of the base fluid. Mineral oils are derived by refining processes, essentially a complex series of purification and separation steps, from crude petroleum oil extracted from the ground. Synthetic base fluids are made by chemical processes, generally by building up larger molecules from smaller ones. Because these chemical reactions and starting materials are well defined, the synthetic fluids are not only relatively pure chemicals but are deliberately made to deliver the performance characteristics required in a lubricant.
Viscosity is a measure of a fluid´s resistance to flow. For lubricating oil in general, viscosity is the most important physical property. It is viscosity, as well as the pressure and speed of movement, which determines the thickness of an oil film between two moving surfaces. This in turn determines the ability of the oil film to keep the two surfaces apart, the rate heat is generated by friction and the rate the oil flows between the surfaces and thus conveys the heat away.
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 this can create more drag and therefore unnecessary heat generation.
Viscosity is also useful for identification of grades of oil and for following the performance of oils in service. An increase in the oil’s viscosity during use usually indicates that the oil has deteriorated to some extent, a decrease normally indicates dilution with fuel. The permissible extent of viscosity increase before corrective measures are taken is largely a matter of experience and judgment of the operator.
SAE stands for the Society of Automotive Engineers, based in the USA. 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; thus SAE 30 is less viscous than SAE 40.
What does the specification API stand for ?
API stands for the American Petroleum Institute. This body has specified the performance standards that oils used in road vehicles should meet, notably for cars and trucks made in the USA. For oils destined for use in passenger car engines, the letters API are followed by a set of two letters such as SJ, etc. This indicates the Service Level for passenger car oils. These specified performance levels have evolved through the years, from API SA to SM, in response to the changes in passenger car engine technology that, in turn, has imposed ever more severe operating conditions on the oil to achieve satisfactory lubrication.
What is a multi-grade oil ?
These are oils designed to give better viscosities at both high and low temperatures than regular mono-grade oils. The viscosity of all oils falls as they get hot – and multi-grade oils are formulated to minimize this effect. Multi-grade oils are defined by a viscosity rating at a low temperature, as well as one at 100 C.
What does synthetic oil mean?
Synthetic motor oils are normally based on synthetic hydrocarbon, manufactured either from ethane gas through polymerization or a multi-phase refining and conversion process. In this way they will be much more resistant to both heat and frost than mineral oils, and their other properties are also most suitable for lubrication purposes. As they are chemically hydrocarbon compounds, the same as mineral oils, they can always be used in place of mineral oils when the most high-class product is desired.
In industrial oils, other synthetic raw materials are also used to a great extent, and they have properties deviating from hydrocarbon. Their use must always be explained separately for each product.
What are synthetic base oils ?
Synthetic base oils are chemicals that have been made, or synthesized, by combining several smaller molecules together. There are several different types, each with its own suite of physical and chemical properties, and each ideal for a selected set of uses in lubrication. Because these are ‘made to design´, and are usually quite pure in composition, the lubricants they are used in can have specific properties which cannot easily be achieved though the use of mineral base oils. This advantage, though, comes at a higher price.
Are synthetic oils better than conventional motor oils ?
In most cases the answer is "yes". Synthetic oils are man made lubricants which were originally created for jet aircraft engines. They have a wide range of performance and can protect engine at very high and very oil temperature conditions. In other words, they have exceptional thermal stability.
The main disadvantage of synthetic lubricants is that they are inherently more expensive than mineral oils. This restricts their use to specialty oils and greases which command premium prices. Coincidentally, oil marketers therefore ensure that their synthetic oils are also capable of the highest performance possible.
Where are these synthetic base oils used?
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 advantages of a multi-grade oil?
A multi-grade oil is one whose proper
• when the vehicle is not being used (for several hours), the engine oil sinks in the crankcase so that, on starting, it takes a certain amount of time (a few microseconds) to again reach all parts of the engine that need to be lubricated. Since a multi-grade oil is more fluid at low temperatures, it reaches the various engine components more quickly than a mono-grade oil, thereby reducing wear on starting.
• Multi-grade oil allow "saving fuel" around 1.5% to 3% then mono-grade oil.
Multi-grade oils provide better engine protection at low and high temperatures than mono-grade oils, in that they maintain optimum viscosity over the engine operating temperature range.
We have come across an oil having a 20W-40 rating. What does ´W´ stand for ?
This is the common terminology used to indicate a multi-grade oil. ´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 lower the temperature the oil can withstand. Thus 10W- indicates a lower viscosity at low temperature than 20W-. The second figure shows the viscosity at 100 C, which is close to the bulk oil temperature in most water-cooled engines.
The highest API for passenger car motor oils today is API-SM.
Similarly, the API designates the performance of diesel engine oils with a letter sequence such as API CF or API CH-4, and for automotive gear oils they use API GL-4.
The highest API for commercial engine oils (diesel oils) today is API CI-4 Plus.
Many other specifications are used to denote lubricant performance: notably the ACEA (European), JASO (Japan) and the US Military classifications.
What are the advantages of a quality oil ?
A good quality oil provides motorists with a number of benefits :
• easier cold start and reduced wear (20 to 30% of engine wear occurs between startup and the time the engine reaches optimal temperature),
• longer engine life,
fuel savings as a result of reduced friction of moving parts and better engine performance.
How do I choose the right oil for my vehicle ?
Selection of the right lubricant is influenced by both the operating conditions and the following criteria, which are important to take into account:
- Right viscosity: (SAE classification)
The engine must start even in extremely low temperatures, and the oil must reliably lubricate the engine also in high temperatures and under heavy load.
- Right quality: (API and/or ACEA classifications)
The oil quality has an impact on the oil change period. The properties of a high-standard motor oil last longer and enable long intervals between oil changes, recommended by the manufacturer. The vehicle manufacturer gives the minimum requirements and the viscosity classifications for the motor oil in the vehicle manual.
You should always consult the car or vehicle manual, issued by the original manufacturer. There you will find the most suitable viscosity grade and performance level. In some cases oils will be mentioned by name.
Then, check the oil pack label to make sure you have the right viscosity grade and that it at least meets the performance level. Note that for many older vehicles the performance level recommended may now have been superseded by newer specifications.
V-Tech Lubricants has, on this website, a large database of cars, trucks, buses which will show you V-Tech recommended products. Furthermore, you can always contact your nearest V-Tech authorized agent who should be able to provide you with advice.
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. This is good maintenance practice. Note that a motor oil that properly lubricates the engine system during the first few thousand kilometers can later become thick and even corrosive after long periods of use. It then cannot flow as required and also blocks the oil filter. This may cause engine damage and seizure in extreme cases. Draining off used oil, following the vehicle manufacturer´s recommended oil change intervals, also removes abrasive metal particles.
Why do oil companies sometimes recommend more than one product for the same application ?
Different drivers and different motoring conditions call for different oils. Thus, a car that is driven under very arduous conditions, with a lot of high-speed motoring, may be better lubricated with a synthetic oil which can better resist the high temperatures.
Can I use diesel engine oil in a petrol engine, and vice versa ?
Petrol and diesel engines have different lubrication requirements. During development, lubricants undergo a number of tests, some common to diesel and petrol engines and others specific to one or the other type, that categorize their performances. At the end of this process, they are awarded an API or ACEA/CCMC compliance standard. These specifications characterize the acceptable functioning of the lubricant in each type of petrol or diesel engine. Lubricants for four-stroke engines usually comply with both petrol and diesel specifications. For example, an API SJ/CF lubricant meets petrol specification SJ and diesel specification CF. But this does not necessarily mean that it will perform in the same way in both petrol and diesel engines. This is why V-Tech has developed specialized ranges, optimized either for petrol or for diesel.
Can I use car engine oil in my motorcycle ?
No, because motorcycle four-stroke engines do not operate under the same conditions as those of cars (higher engine rpm and temperature). The engine lubricant can also be used to lubricate the gearbox and the clutch, which requires a formula with EXTREME-PRESSURE ADDITIVES. On the other hand, passenger vehicle lubricants contain DETERGENT ADDITIVES with a high ash content. In motorcycle engines, these cause deposits to form on the valve train and the piston crowns, which can result in valve burning or piston perforation.
What causes oil pressure to drop ?
During normal vehicle operation, oil is vital to ensures leak tightness between the combustion chamber and the crankcase. The oil pressure indicator shows how well this is being done.
An unusual drop in oil pressure can result from either lower engine oil viscosity due to dilution by fuel (injector problem or use at low load) ; too little oil in the lubrication system (due to an oil leak, excess oil consumption, or failure of the oil circulation pump) ; or even mechanical part wear.
Does the oil have to be topped up ?
The engine oil level should be checked regularly to prevent incidents. A small amount of the oil that circulates in the engine is always burnt (an engine in good condition consumes between 0.2 and 0.5 liters of oil every 1,000 kilometers), but successive top-ups are no substitute for an oil change.
Accordingly, it is natural that an engine consumes a small amount of oil, which can be offset by top-ups between oil changes; however, excessive need for top-ups can be an indication of mechanical problems (leaks, etc).
Which oil should we use in turbo compressed vehicles ?
In order to fulfill the lubrication and shaft cooling needs of the turbo-compressor, oil must answer to very strict criteria. The shaft reaches, a very high temperature, due to the proximity of the exhaust gasses, a very high temperature. Oil must lubricate the shaft continuously otherwise the high temperatures would permanently damage it and the temperature would then very rapidly reach very high levels.
These conditions mean the oil has to offer considerable detergent property, an important resistance to oxidization and deposit formation, but especially very high a thermal stability. The use of SYNTHETIC oils is therefore the most recommended solution in these conditions. Turbo-compressors are characteristic of the diesel engines, as it is very easy for petrol engines to reach the same power level by other means, such as electronic injection, cylinder head multi-valves, etc.
Can you chose another viscosity grade when changing oil ?
Yes, you have to adjust the viscosity according to the conditions of the vehicle´s usage, the environment and the climatic conditions.
Which factors have an impact on oil consumption?
In addition to the mechanical condition of the engine, oil consumption is most affected by the viscosity of the oil used, the volatility of the base oil, the degree of filling and the manner of driving. Usually, thin oil is consumed faster than thicker oil. Thin oil passes through the clearances to the combustion chamber more easily and also to outside of the engine through any leaking seals.
The manner of driving probably has the greatest impact on the oil consumption of a normal engine in good condition when using high quality oil. Oil consumption is increased most by prolonged use of the accelerator pedal with recurrent engine braking; the oil heats up and become thinner, as a result of which the vacuum from the engine braking draws a lot of it into the combustion chamber through the clearances.
Do some oils tend to have higher consumption than others?
Consumption of thin oil is greater than that of thick oil. This is a general rule, but sometimes there are exceptions. For example, when changing the oil grade, consumption may be higher before the first oil change, and a new engine often consumes more oil than normal whilst running in. All in all, the engine should consume some oil, although it is lubricated to a sufficient degree by a very small amount of high-quality motor oil.
How often should the motor oil be changed?
Oil must be changed no later than the maximum number of driven kilometers, given by the car manufacturer. Winter driving, short trips, dusty conditions, etc., require more frequent oil changes. Sufficiently frequent oil changes are the cheapest way of prolonging engine life.
Why are oil changes important?
The oil properties gradually diminish in use and the number of impurities increases. Sufficiently frequent oil changes remove the impurities from the engine and replace them with high-performance oil. The additives in high-performance motor oil help keep the engine clean and prevent corrosion, resulting in less wear and longer engine life. In addition, high-performance oil keeps the engine and catalytic converter in good condition and the lubricating properties of the oil as good as those of new oil. This achieves cleaner exhaust gas emissions and lower fuel consumption.
What do the transmission oil classifications API GL-4 and GL-5 mean?
The API classification for transmission oil defines the anti-wear properties of the oil. The higher the number the more efficient the additives against wear. Oils in the highest GL-5 class are normally used in the so-called hypoid drive gears in the rear axle of rear-driven vehicles, which need as efficient additives as possible. GL-4 oils have less additives and are normally used for the transmission of front-wheel drives.
The API class has to be selected according to the vehicle manufacturer’s instructions. Using too small a class may result in more rapid wear of parts, whereas using too large a class may cause poor synchronization in manual transmission.