Lubricants viscosity grades

Class Types of lubricant Viscosity grade no. BS 4231) Typical application Detailed application Remarks... 

Oil viscosity grades have also been developed with suitable additives for use in a variety of specific appHcations in two-cycle engines, refrigeration and air conditioning, oil mist lubricators, low outdoor temperatures, instmments, and office machines as partially reflected in Table 3. Equipment manufacturers and lubricant suppHers provide recommendations for individual cases. 

Example Multigrade lubricating oils. The viscosity grading of some automotive engine oils is shown in the table below [389]. 

The final chapter, "Environmental issues , addresses lubricant performance and suggests ways to improve fuel efficiency of engines by the use of lower viscosity grade oils and the use of modifiers to reduce metal-metal friction. 

Although petroleum products had been used earlier, their use only became important from the middle of the nineteenth century. They then slowly revolutionised lubrication because of their effectiveness, stability, availability and cheapness, and because of the wide range of viscosity grades which could be easily produced. Vegetable oils and animal fats continued to be used as alternatives, especially where there was a need for high load-carrying capacity or low friction, but otherwise little effort was made to find other types of lubricant for many years. 

Table 8.1 Viscosity grades for industrial lubricants, ISO Standard 3448...

The relative amounts of these components are dependent upon the application, the viscosity grade and the regional performance demand. The key functions of the lubricant and the specific additives used to deliver these functions are described in the following subsections. 

As with other engine lubricants, viscosity is used to divide turbine lubricants into various grades, not by using the SAE classification system but by the lubricant s kinematic viscosity at 100°C. The grades currently available are 3, 4, 5 and 7.5 cSt. Some of the more common specifications used to define these are shown in Table 11.1. 

Specification Issuing authority Viscosity grade Lubricant class Typical applications... 

One of the most critical and often overlooked problems in oil condition monitoring is the introduction of an incorrect lubricant into machinery lubrication systems. Incorrect oil addition ranges from the introduction of foreign materials such as glycol or different base stock fluids to the introduction of similar oil of a different type or viscosity grade. Whilst incorrect oil is not a lubricant failure mode per se, it can be the root cause of real lubrication problems. 

API is not an approval body but certifies lubricant quality, developing its Service Symbol (Fig. 17.1) in 1983, issuing licenses to oil companies for promotion of their lubricants. The symbol s centre circle shows the lubricant SAE viscosity grade, the outer ring upper half contains the API performance classification (only current performance qualities shown, obsolete performance levels may not be used). The outer ring lower half indicates an energy-conserving or fuel economy standard. API s... 

A licensing procedure where lubricant marketers are responsible for product performance and must certify that each viscosity grade of each brand meets requirements. Detailed rules allow for base stock interchange and engine test read across in certain circumstances from one viscosity grade to another. 

Viscosity Grades from Table 17.2, giving lubricant manufacturers freedom to develop lighter grades , such as the 0 W-20 developed for truck fuel economy [2]. 

Each refinery usually produces a limited number (5 to 12) of base stocks, since each base stock requires that there be economically sufficient precursors in the front-end feed and, as well, in the feed to the final fractionation after all processing is complete. In addition, the refinery tries to adjust production rates for individual base stocks to meet their demand. Today, base stocks are classified by their viscosity in square millimeters per second (mm2/s) (or centis-tokes) measured at 40°C and usually employ the International Organization for Standardization (ISO) system for industrial lubricants (ASTM D2422), with a range of 2 to 3200 cSt. Twenty viscosity grades and their ranges are provided in Table 1,6.7... 

M. Johnson, ISO Viscosity Grades, Machinery Lubrication, July 2001. 

Source M. Takizawa, T. Takito, M. Noda, K. Inaba, Y. Yoshizumi, and T. Sasaki, Commercial Production of Two Viscosity Grades VHVH Basestocks, paper presented at the 1993 National Fuels and Lubricants meeting of the National Petroleum Refiners Association, Houston, Texas, November 4-5, 1993. With permission. 

Production of Two Viscosity Grades VHVI Basestocks, paper presented at die 1993 National Fuels and Lubricants meeting of the National Petroleum Refiners Association, Houston, Texas, November... 

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