1 Using ASTM D 2983
2 Additional low-temperature viscosity requirements may be appropriate for fluids intended for use in light duty synchronized manual transmissions.
3 Using ASTM D 445
4 Limit must also be met after testing in CEC L-45-A-99, Method C (20 hours).
5 The precision of ASTM Method D 2983 has not been established for determinations made at temperatures below -40°C. This fact should be taken into consideration in any producer-consumer relationship.

Why the Change

The need for redefined classifications centered on the wide variation in kinematic viscosity possible for SAE 90 and SAE 140 grade lubricant. In the prior version of SAE J306, these ranges were so broad that lubricant viscosity could vary greatly and still technically be in grade. Two new viscosity grades were introduced to cover the upper end of the specifications, SAE 110 and SAE 190. The more narrowly defined classification provides OEMs with greater flexibility in specifying a viscosity grade to ensure an optimal balance of fuel economy and durability for their equipment.

In addition, under the old designations, an axle could be serviced with a lubricant having a viscosity significantly lower or higher than the lubricant with which the axle was validated. To prevent the axle from being filled with a lubricant with too low a viscosity, an OEM was forced to specify a higher viscosity grade than actually desired.

For example, under the old classifications, if the optimum 100°C viscosity for an axle was 19.5 cSt, the OEM would normally specify an SAE 90 lubricant. However, the actual viscosity of this lubricant could be as low as 13.5 cSt, which might be too low to provide the required durability. To prevent this problem, the OEM would recommend an SAE 140 grade lubricant, ensuring that viscosity would never fall below 19.5 cSt. Unfortunately, that also means viscosity could be as high as 41.0 cSt, possibly resulting in poor fuel economy or shift problems. Under the new limits, the OEM would recommend SAE 110 grade lubricant, which meets the 19.5 cSt requirements and ensures that the axle is serviced with a lubricant having a viscosity no higher than 31 cSt.

back to top 

A Question of Balance

OEMs are challenged today to meet the often conflicting demands for improved fuel economy coupled with improved axle durability. Government regulations are dictating better fuel economy, while vehicle owners are demanding increased performance. Engine horsepower has increased by 34% over the last decade, but axle gear sizes have remained constant, sump capacities have been reduced, and drain intervals have been extended. These demanding conditions can be met only by axle lubricants that provide enhanced durability protection.

Axle efficiency can be improved by using lower viscosity fluids (such as SAE 75W-90), which minimize frictional churning losses. However, light trucks and SUVs are often used in conditions that expose axles to heavy loads or high operating temperatures. These conditions require superior axle protection, often provided by choosing a heavier viscosity fluid (SAE 75W-140, for example). Commercial vehicle applications may have even more stringent durability requirements. However, providing high durability and long vehicle life often reduces fuel efficiency.

The new viscosity classifications provide more flexibility for OEMs to select the optimum viscosity grade for an application. For example, the SAE 110 grade should be useful in an SUV or light duty truck where improved fuel economy is important but high torque or durability at high speed operation is essential. This new classification should aid OEMs in specifying a fluid viscosity more tightly to ensure that the lubricant has the intended physical properties for a given application.

The SAE 190 grade may allow better efficiency and enable multigrade performance in severe duty applications where high film strengths are needed. These end uses may include applications such as construction equipment operated in extreme temperature environments. The end result is a better match of fluid performance to axle needs.

back to top 

Your Labels May Need To Change

The revised SAE J306 may cause some labeling issues in the marketplace. Lubricants should be labeled according to the guidelines of the revised standards. The problem is that lubricants blended to the high end of the old ranges may be on the market labeled as SAE 90 or SAE 140, when they are really SAE 110 or SAE 190 lubricants. Lubricant manufacturers should examine their records and adjust their labels to reflect the viscosity ranges described in the updated SAE J306 standard.

back to top 

The Lubrizol Advantage - The Right Blend of Performance

Formulating an automotive gear oil is no easy task. Optimizing a lubricant for a particular application requires an in-depth understanding of the relationships between fluid characteristics and axle design. Getting just the right blend of base fluid, performance additives and viscosity modifier performance involves a delicate balancing act to ensure both efficient operation and long equipment life.

Lubrizol supplies a wide variety of performance enhancing additives that help gear oil suppliers deliver just the right lubricant for an application. For applications where manufacturers specify low viscosity lubricants, Lubrizol technology can enhance the durability of lower viscosity base fluids with a variety of products, including extreme pressure antiwear additives that prevent wear, pitting, spalling, scoring, scuffing and other types of distress that can cause equipment failure and downtime. For applications where a high viscosity lubricant is required, we can provide performance additives that improve the efficiency of the finished lubricant.

back to top 

Shear Stability Performance

Another key area that Lubrizol technology excels in is resistance to shear. Shear stability is taking on greater importance because of the increased use of wide-span multigrade lubricants to improve fuel economy, shiftability and service life, and stay-in-grade performance is part of the SAE J306 standard. These lubricants typically contain high levels of polymer, which can shear in service, reducing viscosity, decreasing the protective fluid film and increasing the potential for premature equipment failure. Lubrizol supplies highly shear stable viscosity modifiers that resist the tendency to shear in service, thereby maintaining a high level of protection and performance for the life of the equipment.

Lubrizol leads the industry in developing performance additive packages that meet the changing needs of OEMs and end-users worldwide. Lubrizol's commitment to research, development and testing, in both the laboratory and the field, ensures that we will continue to deliver products that keep light duty cars and trucks, heavy duty commercial vehicles and heavy equipment running reliably and efficiently for years to come.

back to top