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Engine Oil Classifications
There are literally hundreds of engine oil specifications and classifications used when describing the performance and properties of engine oils. Manufacturers will quote a variety of these specs, so it is important to be familiar with at least the most common systems.

Basically, we are likely to encounter 6 types of grading systems;

• API Engine Service Classification
• ILSAC Grades
• Military Engine Oil Classification
• CCMC Engine Oil Service Classification
• ACEA Engine Oil Service Classification
• A Host of OEM Specifications

Mobil Material Data Sheets
Click here to visit the Mobil Material Data Sheets website. From this site, you can search, view, print and download MSDSs for selected Mobil products. The collections of MSDSs listed are for commercially available products for a number of Mobil companies, world-wide.The documents within a given collection are designed to meet the requirements of that country.

Oil Consumption
Oil is lost in the engine in three main ways:
• By burning the combustion chamber
• By leakage in liquid form
• By passing out of the crankcase in the form of mist, which in the closed crankcase ventilating system will also be burned in the combustion chambers.

Two main factors affect oil consumption:
• Engine speed
• Amount of wear on engine parts

High speed produces temperature. This in turn lowers the viscosity of the oil so that it can move more easily past the piston rings into the combustion chamber, where it is burned. In addition, the high speed exerts a centrifugal effect on the oil that is feeding through the oil lines drilled in the crankshaft to the connecting - rod journals. Thus, more oil is fed to the bearings and subsequently thrown on the cylinder walls.

At high speeds, particularly in a worn engine, the oil control rings cannot function effectively, so that more oil finds its way into the combustion chamber. Crankcase ventilation causes more air to pass through the crankcase at high speeds and this causes more oil to be lost in the form of mist.

As engine parts wear, oil consumption increases. Worn crankcase bearings tend to throw more oil on to the cylinder walls. Tapered and worn cylinder walls prevent normal oil control ring action. The rings cannot shape rapidly enough to conform with the worn cylinder walls as the rings move up and down. More oil consequently gets into the combustion chamber, where it burns and fouls spark plugs, valves, rings and pistons. Carbon formation aggravates the condition, since it further reduces the effectiveness of the oil control rings.

Where cylinder wall wear is not excessive, installation of special oil control rings reduces oil consumption by improving the wiping action so that less oil can move past the rings.

Worn intake - valves guides will also increase oil consumption because oil will leak past the valve sterns and will be drawn into the combustion chamber with the air-fuel mixture every time the intake valves open. Installation of new valve stern seals or where necessary new valve guides, or reaming of guides and installation of valves with oversize sterns will reduce oil consumption from this cause.

Oil consumption will also occur if the incorrect viscosity of oil is selected for an engine or the oil is allowed to be used past its recommended oil change period. Also, on super charged engines, leaking super charger rotor shaft seals is another source of excessive oil entering the combustion chamber increasing oil consumption.

API Engine Service Classification
Most readers will be familiar with the American Petroleum Institute's (API) method of communicating between the engine manufacturers, oil companies and engine owners. The API system is divided into two major categories. The "S" series (i.e. SF, SG, SH, SJ) is used for classing petrol engine oils, while the "C" series (i.e. CE, CF -4, CH 4) refers to Diesel engine oil specs. Basically the higher the letter following the S or C, the better the performance in either Petrol or Diesel engine respectively.

The highest API petrol engine oil spec is currently SJ, while for diesel oils it is CH 4. An oil will often pass both a "S" and "C" classification, for example SJ/CH 4.

Ford and General Motors now recommend the use of GF2 oils in vehicles such as AU Falcon and VT Commodore. GF2 represents the highest quality petrol engine oils designed to give excellent engine protection as well as enhancing fuel economy.

Separating fact from fiction
There are many myths relating to lubricants these can lead to problems as advice offered can be totally incorrect and therefore damaging to machinery and engines so to help you separate fact from fiction here is some straight talk about common lubrication myths

Myth No. 1: Oil is oil.
Some characteristics differ obviously between oils - for example, viscosity. But other differences are not so obvious. There are hundreds of industrial lubricants, each formulated for specific applications, and each contains additives specially blended for those applications. Using the wrong lubricant is a major cause of lubricant-related machine breakdowns. Using the right lubricant can help improve machine efficiency and extend component life.

Myth No. 2: Oil never wears out.
Oil does wear out. The primary enemy of oil life is heat. At operating temperatures of 150 F and higher, oil begins to oxidize and thicken. Sooner or later, depending on oil quality and operating temperature, the oil will leave a trail of sludge and varnish throughout the machine. To prevent sludge and varnish, change the oil every six months in machines that operate at high temperatures, and every year in others. Some oil suppliers will take regular oil samples from critical industrial machines, run them through a battery of tests, and provide a report on oil condition. Such reports can pinpoint the right change intervals.

Myth No. 3: Old oil is the primary cause of lubricant-related equipment breakdowns.
The two most prevalent causes of lubricant-related breakdowns are: (1) use of the wrong lubricant, and (2) high concentrations of contaminants, especially dirt and metalwear particles that bombard machine components and cause premature wear and breakdowns. Again, monitor the condition of the oil. Testing can identify metal-wear particles and warn of impending breakdowns.

Myth No. 4: Viscosity determines the lubricity, or "oiliness," of an oil.
Heavier oils do form thicker lubricating films, but in today's oils, additives also provide lubricity. Addition of fatty materials increases lubricity without necessarily increasing viscosity. Sulfate and metallic lubricity additives have no significant effect on viscosity.

Myth No. 5: Oils of the same SAE or ISO numbers are interchangeable.
SAE and ISO numbers are intended only as guidelines in selecting the proper viscosity. They tell nothing about other characteristics. A hydraulic oil and a motor oil with the same SAE number, for example, may have the same viscosity, but they cannot be used interchangeably.

Myth No. 6: An increase in viscosity always indicates an increase in harmful insolubles.
Detergent-dispersant additives can keep a substantial volume of insolubles in fine, uniform particles distributed throughout the body of oil so they will not form sludge or harmful deposits; viscosity increases but no harm is done. Eventually, however, the oil can carry no more of the potentially harmful insolubles. Viscosity tests indicate when that point (the "condemning limit") has been reached.

Myth No. 7: An oil's only job is to lubricate.
In many applications, oil must also flush away dirt and wear particles and carry them to the machine's filters. Oil also dissipates heat. Both oil and grease may help seal bearings to prevent the entry of contaminants.

Myth No. 8: If a little oil or grease is good, a lot is better.
Applying too much grease can rupture seals and thus allow contaminants to enter the machine. In an electric motor bearing, the grease can also penetrate the motor windings and cause the motor to burn out. Excessive grease in a bearing can also generate heat because fluid resistance is greater, contributing to a costly bearing failure.

Excessive oil can also generate heat because of increased fluid resistance; this heat shortens oil life. Overflowing reservoirs--sometimes noticeable only after the machine stops and all oil has returned to the reservoir--can contaminate the process and create unsafe work conditions. Overfilling splash systems can rupture seals.

Myth No. 9: The cleaner the oil is, the better the oil is.
In some cases, a dirty oil is satisfactory. Internal combustion engines, for example, create large amounts of unburned carbon and other materials that are carried in suspension in the oil until they can be deposited in the filter or the oil can be changed. Here, a dirty oil is probably doing its job. But in hydraulic systems in numerical control machines, even minute amounts of contaminants are intolerable because they quickly clog the servovalves.

In short, for some applications the oil should look dirty, and for others, it must be clean. Monitoring oil condition is always advisable.

Myth No. 10: Hydraulic oil isn't good lubricant.
Although many people believe that hydraulic oil is in a class of its own, it is still an oil. In addition to providing a means of transmitting energy, it lubricates hydraulic pumps, bearings, cylinders and other system components. It must be of high quality because hydraulic systems demand a lot from an oil--long oil life, pump protection, oxidation resistance, antiwear properties, and more.

Myth No. 11: Grease colour has a lot to do with grease quality.
The colour of grease has nothing to do with quality. A dull, brownish-grey grease can be just as effective as a sparkling red grease. Colour is used only as a control in lubricant manufacturing or when a plant desires a specific colour.

Myth No. 12: Lubrication is a costly headache.
Lubrication, when compared to the cost of downtime, is not costly. In plant after plant, machine breakdowns can be traced to half-hearted or unsystematic lubrication practices. When these same plants have tightened their lubrication practices, they have seen downtime rates plummet, production increase, and overall operations run more smoothly.

Myth No. 13: When it comes to lubrication, nothing is new.
Industrial machines have been getting more powerful and more complicated, and industrial lubrication has had to keep in step with technology. For example, synthetic oils have been developed to meet the simultaneous demands of high power machines and energy conservation. Today's lubricants offer superior performance and, because they last longer, lower application costs.

Forgetting all these myths, and selecting lubricants on the basis of performance and using them as long as they are doing their job safely, will help hold down the rising cost of maintenance.