Viscosity is a measure of a fluid's resistance to flow. A fluid with low viscosity flows easily and is often called "thin." Water is an example of a fluid with a relatively low viscosity. A fluid with high viscosity is often described as "thick." Maple syrup is an example of a fluid with a relatively high viscosity.

"Motor oil breaks down over time. When it breaks down, it loses its effectiveness and can no longer properly protect your engine.In addition to lubricating an engine's moving parts, motor oil is designed to carry combustion byproducts away from the pistons and cylinders. It is designed to deal with the small amounts of water that form as the engine heats and cools, and to collect the dirt and dust that enter the engine through the air-intake system. It also handles acids that are formed by the reaction between water and other contaminants. Sometimes there are even fuel leaks (fuel dilution) or coolant leaks that get into the oil system.As a car is driven, the level of contamination in the motor oil constantly increases. The oil filter removes particles as the oil passes through the filter, but over time an oil's additives are used up and the oil itself can start to degrade (oxidize or thicken). At that point, the oil can no longer do its job and must be changed.The rate at which contamination and additive depletion occurs depends on many variables. One of these is driving conditions, which vary greatly and have a direct effect on the useful life of the oil. Other factors include the precision of ignition, fuel injection or carburetion adjustments, air cleaner service, and the general mechanical condition of the engine.Oil should be changed before the contamination level reaches the point where engine damage can result. Because it is difficult for the individual motorist to determine when the contamination level is too high, automobile manufacturers provide recommended oil change intervals. These change recommendations vary by model year and manufacturer. Recommended intervals and mileage limits also vary with the type of service under which a car operates. More frequent oil changes are recommended for severe service."

"Engineers work to establish an optimal viscosity for an oil, based on load and speed conditions. They balance lighter – or low-viscosity – oil, which provides little resistance to motion thereby saving fuel and efficiently transferring horsepower, with a heavier – or high-viscosity – oil that resists being squeezed out of the contact area between metal surfaces, or leaking.The complicating factor is that the viscosity of an oil varies with changes in temperature – thinner when hot, thicker when cold. At low temperatures, we need the motor oil to flow readily (not thicken too much or gel). At high temperatures, we need the motor oil to keep from becoming too thin and allowing metal-to-metal contact. Therefore, engineers developed multigrade motor oils."

Engine oils are currently classified by a two-letter code. Gasoline engine oil categories start with the letter S (originally designated "Spark Ignition" engine oils, we now associate the S with "Service"). Diesel engine oil categories start with the letter C (originally designated "Compression Ignition" engine oils, we now associate the C with "Commercial"). The second letter is simply a sequential designation of improving quality levels over time. In other words, when a new industry quality level is established, the next letter of the alphabet is used (so SN replaced SM). The letters "I" and "K" were purposefully skipped to eliminate potential confusion with other commonly used designations.

The viscosity index (VI) number is a measure of the relative change in viscosity of oil over a temperature range. The HIGHER the viscosity index, the SMALLER the viscosity change over temperature. The VI is not related to the actual viscosity or SAE viscosity, but it is a measure of the rate of viscosity change. The VI number is typically used only as an indicator. The actual performance results of low-temperature pumpability tests and high-temperature wear tests of a motor oil are better predictors of good performance in an engine. Generally, multigrade oils (0W-40, 10W-30, etc.) will have high viscosity indexes. Monograde oils (SAE 30, 40, etc.) will have lower viscosity indexes.

In simple language, the first part of the viscosity designation (W grade) is an indication of the product's ability to help an engine crank and start and for the engine to pump the lubricant. The lower the number (0W is the lowest), the lower the temperature at which the product can be used. So the W grade is related to the lowest temperature your engine sees when you start the engine on the coldest morning of the year. But also keep in mind that a lower W grade pumps and helps an engine to start better than a higher W grade. The second part of the viscosity grade is related to the viscosity your engine sees at operating temperature. In this case, a higher number is a higher viscosity grade and provides more viscous oil at operating temperature than lower viscosity grade oil. It is not safe to assume that a higher viscosity oil is always better for your engine because other factors, such as engine design, fuel economy and power, are also related to operating viscosity. You should always consult your owner's manual for the right oil to use for your particular engine. For more information on the viscosity grade specifications, a quick search of the Internet will identify several websites where information about SAE J300 (Viscosity Properties Test) can be found.

In simple language, the first part of the viscosity designation (W grade) is an indication of the product's ability to help an engine crank and start and for the engine to pump the lubricant. The lower the number (0W is the lowest), the lower the temperature at which the product can be used. So the W grade is related to the lowest temperature your engine sees when you start the engine on the coldest morning of the year. But also keep in mind that a lower W grade pumps and helps an engine to start better than a higher W grade. The second part of the viscosity grade is related to the viscosity your engine sees at operating temperature. In this case, a higher number is a higher viscosity grade and provides more viscous oil at operating temperature than lower viscosity grade oil. It is not safe to assume that a higher viscosity oil is always better for your engine because other factors, such as engine design, fuel economy and power, are also related to operating viscosity. You should always consult your owner's manual for the right oil to use for your particular engine. For more information on the viscosity grade specifications, a quick search of the Internet will identify several websites where information about SAE J300 (Viscosity Properties Test) can be found.

In simple language, the first part of the viscosity designation (W grade) is an indication of the product's ability to help an engine crank and start and for the engine to pump the lubricant. The lower the number (0W is the lowest), the lower the temperature at which the product can be used. So the W grade is related to the lowest temperature your engine sees when you start the engine on the coldest morning of the year. But also keep in mind that a lower W grade pumps and helps an engine to start better than a higher W grade. The second part of the viscosity grade is related to the viscosity your engine sees at operating temperature. In this case, a higher number is a higher viscosity grade and provides more viscous oil at operating temperature than lower viscosity grade oil. It is not safe to assume that a higher viscosity oil is always better for your engine because other factors, such as engine design, fuel economy and power, are also related to operating viscosity. You should always consult your owner's manual for the right oil to use for your particular engine. For more information on the viscosity grade specifications, a quick search of the Internet will identify several websites where information about SAE J300 (Viscosity Properties Test) can be found.

Synthetic products are produced by chemical reactions in which pressure, temperature and the ratio of component elements are carefully controlled. This results in a pure compound with maximized lubricating properties, which can lead to enhanced energy efficiency, improved equipment protection, more reliable equipment performance and extended oil service life.

In the most general form, the following formula can be used to determine your cost savings: Savings over time = (costs associated with lubricant A) – (costs associated with lubricant B). However, it is important to understand how to properly account for ALL of the costs of a lubricant. This article explains the primary factors to consider.

There are several Mobil industrial lubricants that are safe for the food service industry. These include the Mobil SHC Cibus™ Series, Mobil SHC Polyrex™ Series, Mobil Synturion™ 6, Mobil Rarus™ PE, Mobil Gargolye™, Mobil™ SM 16M and Mobilgrease™ FM Series lubricants.

All of these products use advanced proprietary formulations designed to provide excellent protection from micropitting fatigue wear, as well as high resistance to traditional scuffing wear. Mobil SHC Gear Series also maintains the latest approvals from OEMs for gear boxes in industrial applications. Mobilgear SHC XMP 320 has long been our recommended oil for lubrication of the main gearbox in wind turbine applications, due to its proven oxidation performance over time. Its durability provides extended drain intervals required for the extreme wind turbine application. Mobil SHC Gear 320 WT is a more recent addition to our Mobil Industrial Lubricant product line and offers an enhancement for wind turbine gear boxes – above and beyond the performance of Mobilgear SHC XMP 320. Mobil SHC Gear 320 WT has improved oxidative stability and higher viscosity index compared to Mobilgear SHC XMP 320, enabling improved low temperature performance and well as oil life.

If not handled and stored properly, lubricating oils and greases can deteriorate or become contaminated. You can find a detailed explanation of indoor, outdoor and bulk storage recommendations here or contact your distributor for more information.

Shelf life represents the time period during which a stored product, such as lubricating oils and greases, can continue to be used without quality-control checks to verify performance attributes. For more information please consult the Technical Topic titled “Shelf life recommendations for lubrication oils and greases.”

Typically, equipment builders’ manuals include a recommendation on oil change intervals and other related maintenance schedules. We also recommend using tools such as Mobil Serv℠ Lubricant Analysis to determine whether in-service oil requires replacement. Read more about our Mobil Serv Lubricant Analysis program or contact your distributor for more information.

There is a fundamental difference between product life in storage and product life in service. During storage, the packaged product generally remains motionless for extended periods, and can be exposed to cyclic variation in temperature and other environmental conditions such as vibration, which can impact the components of the formulation or potentially allow ingress of contaminants from the environment – both of which have the potential to affect the product’s performance characteristics. However, when the lubricant is in service, it is exposed to the dynamic conditions of the lubricated system (e.g., circulation, splashing, churning, etc.). Once a product has been placed in service, its suitability for continued use becomes a function of other factors. For more information please consult the Technical Topic titled “Shelf life recommendations for lubrication oils and greases.”

In general, the recommended shelf life for oils and greases is five years, when stored properly in the original sealed containers. However, a variety of factors can impact recommended shelf life. You can find a detailed shelf life explanation here. 

The lubricating oil and grease shelf life recommendation provided by ExxonMobil applies to products stored in the original sealed containers in a sheltered environment under good housekeeping conditions and at typical ambient temperatures. For more information please consult the Technical Topic titled “Shelf life recommendations for lubrication oils and greases.”

Be sure to clean up all excess grease and dirt from the bearing and surrounding areas. Excess grease and dirt on external surfaces acts as an insulator and prevents heat dissipation. Additionally, excess grease on the external surfaces and floors can introduce a safety hazard to personnel. For more information please consult the Technical Topic titled "Regreasing rolling element bearings."

Ahead of applying a new grease, thoroughly clean – or flush out – the previous grease from the bearing. This avoids compatibility issues and helps ensure that the new grease can perform at an optimum level. If this cannot be carried out, mitigating actions should focus on minimizing the amount of the displaced grease remaining in the application, such as by increasing relubrication frequency to facilitate a purge of old grease in a timely manner. For more information please consult the Technical Topic titled "Grease compatibility."

Mixing different greases, even those with similar thickener types, can sometimes lead to ineffective lubrication resulting in damage of the lubricated components. If not spotted soon enough this may lead to equipment failure. For specific information please consult the Technical Topic titled "Grease compatibility."

Mixing different types of greases can sometimes lead to incompatibility problems. Grease incompatibility results from chemical interactions between the thickener or additive systems of the dissimilar greases. In some cases, grease incompatibility can lead to equipment failure or damage of the lubricated components. Mixtures of incompatible greases will exhibit either excessive hardening or softening relative to the consistency of the individual pure greases. The hardening or softening tendencies of the mixture will generally become more pronounced as the operating temperature increases or as the rate of shearing on the grease mixture increases. Incompatible greases may also exhibit excessive oil separation or “bleeding” tendencies at higher temperatures. For more information please consult the Technical Topic titled “Grease compatibility.”

Many rolling element bearings require relubrication of small quantities of grease between grease flushing intervals. This is best done with a low-pressure grease gun. If seals are in good condition, the quantity of grease needed may be small and infrequent. Check the amount of grease in the bearing – remove fitting or grease plug to allow excess grease to come out. Check bearings and seals for excess leakage. Apply a few “shots” of grease at a time. For more information please consult the Technical Topic titled "Regreasing rolling element bearings."

Greases may show deterioration in one or more of the following ways: Excessive oil separation Some “bleed” is normal and required (see Technical Topic titled “Grease static oil bleed”) Significant change (>25 percent) in the grease consistency as measured by worked or unworked penetration. Grease consistency affects the ease of grease application, low-temperature performance and stayput performance, all critical characteristics ensuring proper grease lubrication. In technical terms, grease’s consistency is referred to as its NLGI Grade – from NLGI 000 (semifluid) to NLGI 6 (block – very firm) Significant change in color or odor Noticeable change in texture For more information please consult the Technical Topic titled “Shelf life recommendations for lubrication oils and greases."

Many rolling element bearings require relubrication of small quantities of grease between grease flushing intervals. This is best done with a low-pressure grease gun. If seals are in good condition, the quantity of grease needed may be small and infrequent. Check the amount of grease in the bearing – remove fitting or grease plug to allow excess grease to come out. Check bearings and seals for excess leakage. Apply a few “shots” of grease at a time. For more information please consult the Technical Topic titled "Regreasing rolling element bearings."

Where bearings are subject to contamination, more frequent relubrication may be necessary. Contamination will lead to unusual operation such as hot, noisy, vibrating or leaking bearings. Be sure to spot, report and act on those. For more information please consult the Technical Topic titled “Regreasing rolling element bearings.”

How much grease should be applied? Bearing manufacturers frequently recommend the amount of grease to apply to a bearing by weight or volume. The grease gun can be calibrated by counting the number of shots to dispense a known amount of grease. For more information please consult the Technical Topic titled “Guide to electric motor bearing lubrication.”

Unfortunately, there's no one single answer, because there's a long list of factors that influence relubrication frequency. Generally, the smaller the bearing and faster the speed, the less frequent the interval for relubrication with grease. Larger, slower bearings require more frequent relubrication. Different types of bearings require different relubrication frequencies: Radial ball = base interval Cylindrical roller = 5 times as frequent Thrust-ball and roller = 10 times as frequent For more information please consult the Technical Topic titled “Regreasing rolling element bearings.”

An insufficient amount of grease could lead to bearing failure due to lack of lubrication. On the other hand, over-lubrication can also lead to bearing failure and cause problems due to migration of the lubricant into the windings. For more information please consult the Technical Topic titled “Guide to electric motor bearing lubrication.”

Higher temperatures increase a grease oxidation rate, typically doubling it for every 10°C (18°F) rise above 65°C (150°F). Grease softens as temperatures increase and may become fluid enough to leak out of housings. And oil separation and volatility also increase with temperature. Therefore, high temperature operation requires relubrication more often; high-temperature greases that have the capability to maintain structural stability, oil separation, volatility and oxidation under control can help extend that frequency. For more information please consult the Technical Topic titled “Guide to electric motor bearing lubrication.”

Intervention on machinery requires a prior risk analysis to identify potential mishaps during or as a consequence of the maintenance, and therefore determine a safe sequence of events and required protective gears. Beware in particular of high pressure buildup in the dispensing devices or in the bearing when conducting regreasing operations.

During application, first check the amount of grease in the bearing by removing the fitting or grease plug and see if any grease is released. Then check the bearings and seals for any excess leakages. For more information please consult the Technical Topic titled “Regreasing rolling element bearings.”

Yes, with the following conditions: If the amount of oil is small, covering only low spots in the surface of the grease. The grease readily absorbs the oil upon stirring. For more information please consult the Technical Topic titled “Grease static oil bleed.”

Absolutely. Like a blood test, used oil analysis gives critical insights into the condition and performance of the lubricants being used in a machine, helping detect any issues before major damage is done.

That depends on the package you are using. Our new Mobil Serv™ Lubricant Analysis program uses the latest technologies to make the sampling process as quick as possible. For example, we have eliminated the need for manual sample labelling by introducing pre-labelled bottles with QR codes and a unique number identifier. Our customers are already seeing the benefits. Recently we were able to help an alumina production plant reduce time spent on oil analysis by nearly 200 labour hours, with related savings of US $9,600.

That depends on the package you are using. Our new Mobil Serv™ Lubricant Analysis program uses the latest technologies to make the sampling process as quick as possible. For example, we have eliminated the need for manual sample labelling by introducing pre-labelled bottles with QR codes and a unique number identifier. Our customers are already seeing the benefits. Recently we were able to help an alumina production plant reduce time spent on oil analysis by nearly 200 labour hours, with related savings of US $9,600.

Our field-based lubrication engineers offer expert advice on sound lubrication practices, proper lubricant selection, equipment troubleshooting and other lubrication services that can help equipment run longer and more efficiently. Learn more about our Engineering Services here, or through your distributor.

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You can find contact information for our technical help desk locations here.