DF Sales&Marketing
Oil Tech Moderator
in part from lubes ’ n greases magazine
Going back to a now well-worn and crumpled report on 1980 lubricant sales from the national petrochemical & refiners association, I see that straight grades (such as sae 20 and sae 30) accounted for about 52 percent of u.s. Engine oil sales. By 1990, the volume had dropped to around 28 percent and by 2000 it was 11 percent. In the final year for which npra published comprehensive volume data (2006), their share had dropped to almost 4 percent. In all years, total engine oil sales volume was on the order of 1 billion gallons per year.
During December’s astm committee d2 in anaheim, calif., the American petroleum institute’s heavy-duty engine oil categories that currently support straight grade engine oils were declared to be obsolete. Effective at the end of 2009, api categories cf-2 and cg-4 are gone. Api cf-4 already had been dropped in June 2008. These categories, all introduced in the first half of the 1990’s, died because the engines used to test for compliance are no longer available.
A post-mortem exam of straight grades might begin with the question, what happened? What factors drove the steady change from mono-grades to multi-grades, and what impact will this have on future sales of engine oil and related products?
why they’re dying
Single-grade engine oils were the only game in town until the mid-1950’s, when the first viscosity index improved engine oils appeared. V.I. Improvers were probably novelties when they debuted, but as time went on, it became apparent that multigrade engine oils offered some benefits that were not available in straight grades. For one thing, it wasn’t necessary to change oil grades for winter or summer service. They were a great sales tool, and gave oil marketers a chance to potentially improve margins.
Gradually, the auto manufacturers began to move to multigrade recommendations for their engines to gain the advantages of cold-start capability. GM owners manuals last referenced straight grade engine oils in 1983—and then only for use in “warm” temperatures. With the energy crisis and air quality standards which came in the ‘70s, lower-viscosity engine oils became more important.
One technology that virtually demanded multi-viscosity engine oils was the four-cylinder engine. Since there is only one ignition stroke for each crankshaft revolution, starting and maintaining the start became a real issue. The starter could easily turn the engine fast enough to get it to start but, if the oil was too thick (read “straight grade”) the engine would immediately stall. The simple solution was to use multi-vis engine oils, which flowed well at both higher and lower temperatures. Since then, the push has been to lower and lower viscosity.
On the heavy-duty side, the change was slower in coming. The straight-grade market remained strong for a number of years, primarily supported by detroit diesel’s two-cycle engine market. In fact, it wasn’t until dd introduced its first four cycle engine series that it even recommended multigrade engine oils. There was some validity in this position, especially for the company’s large displacement engines. I have seen power curves generated on 16v-149 detroit diesel engines that clearly showed a loss in power at higher output when multi-grade engine oils were used.
However, the major over the road engine manufacturers all saw the advantages of multigrade engine oils. One of the clearest benefits to be identified was reduced oil consumption with multi-grades.
On the face of it, that seems illogical (you’d expect heavier oils to stay put) but it is true. Multigrades form a thinner—but still adequate—oil film on cylinder liner walls, so when the piston moves up in its travel, there is less oil to push into the combustion chamber to be consumed.
There’s another problem with straight-grade engine oils in heavy-duty applications: they tend to form more deposits than do multigrades. This is probably due to the use of higher-vis base stock cuts in straight grades.
Of course, the question of emissions also comes into play for the heavy-duty engine oems. Progressively more stringent emissions requirements make control of oil consumption critical since that is the most common oil-related contribution to emissions. Volatility is important, too, but the fact of reduced consumption due to oil film thickness is a critically important part of the equation.
fallout for other products
So now we are down to 4 percent or less of u.s. Automotive engine oil sales being straight grades. Some product applications that May still depend on these oils are certain transmission fluids, hydraulic oils, gear oils and general purpose lubricants. Each of these applications, if they haven’t already, will need to find replacement products and specifications to cover their former use of straight-grade engine oils, once they are finally obsolete.
Groups that write standards for gear oil and transmission fluid, for example, will have to review their existing standards to see if these orphaned applications can be covered by other specifications. Hydraulic fluids are already covered with proper viscosity grades. For general purpose products, users will have to search the product lines to find suitable substitutes.
(please continue to part 2)
Going back to a now well-worn and crumpled report on 1980 lubricant sales from the national petrochemical & refiners association, I see that straight grades (such as sae 20 and sae 30) accounted for about 52 percent of u.s. Engine oil sales. By 1990, the volume had dropped to around 28 percent and by 2000 it was 11 percent. In the final year for which npra published comprehensive volume data (2006), their share had dropped to almost 4 percent. In all years, total engine oil sales volume was on the order of 1 billion gallons per year.
During December’s astm committee d2 in anaheim, calif., the American petroleum institute’s heavy-duty engine oil categories that currently support straight grade engine oils were declared to be obsolete. Effective at the end of 2009, api categories cf-2 and cg-4 are gone. Api cf-4 already had been dropped in June 2008. These categories, all introduced in the first half of the 1990’s, died because the engines used to test for compliance are no longer available.
A post-mortem exam of straight grades might begin with the question, what happened? What factors drove the steady change from mono-grades to multi-grades, and what impact will this have on future sales of engine oil and related products?
why they’re dying
Single-grade engine oils were the only game in town until the mid-1950’s, when the first viscosity index improved engine oils appeared. V.I. Improvers were probably novelties when they debuted, but as time went on, it became apparent that multigrade engine oils offered some benefits that were not available in straight grades. For one thing, it wasn’t necessary to change oil grades for winter or summer service. They were a great sales tool, and gave oil marketers a chance to potentially improve margins.
Gradually, the auto manufacturers began to move to multigrade recommendations for their engines to gain the advantages of cold-start capability. GM owners manuals last referenced straight grade engine oils in 1983—and then only for use in “warm” temperatures. With the energy crisis and air quality standards which came in the ‘70s, lower-viscosity engine oils became more important.
One technology that virtually demanded multi-viscosity engine oils was the four-cylinder engine. Since there is only one ignition stroke for each crankshaft revolution, starting and maintaining the start became a real issue. The starter could easily turn the engine fast enough to get it to start but, if the oil was too thick (read “straight grade”) the engine would immediately stall. The simple solution was to use multi-vis engine oils, which flowed well at both higher and lower temperatures. Since then, the push has been to lower and lower viscosity.
On the heavy-duty side, the change was slower in coming. The straight-grade market remained strong for a number of years, primarily supported by detroit diesel’s two-cycle engine market. In fact, it wasn’t until dd introduced its first four cycle engine series that it even recommended multigrade engine oils. There was some validity in this position, especially for the company’s large displacement engines. I have seen power curves generated on 16v-149 detroit diesel engines that clearly showed a loss in power at higher output when multi-grade engine oils were used.
However, the major over the road engine manufacturers all saw the advantages of multigrade engine oils. One of the clearest benefits to be identified was reduced oil consumption with multi-grades.
On the face of it, that seems illogical (you’d expect heavier oils to stay put) but it is true. Multigrades form a thinner—but still adequate—oil film on cylinder liner walls, so when the piston moves up in its travel, there is less oil to push into the combustion chamber to be consumed.
There’s another problem with straight-grade engine oils in heavy-duty applications: they tend to form more deposits than do multigrades. This is probably due to the use of higher-vis base stock cuts in straight grades.
Of course, the question of emissions also comes into play for the heavy-duty engine oems. Progressively more stringent emissions requirements make control of oil consumption critical since that is the most common oil-related contribution to emissions. Volatility is important, too, but the fact of reduced consumption due to oil film thickness is a critically important part of the equation.
fallout for other products
So now we are down to 4 percent or less of u.s. Automotive engine oil sales being straight grades. Some product applications that May still depend on these oils are certain transmission fluids, hydraulic oils, gear oils and general purpose lubricants. Each of these applications, if they haven’t already, will need to find replacement products and specifications to cover their former use of straight-grade engine oils, once they are finally obsolete.
Groups that write standards for gear oil and transmission fluid, for example, will have to review their existing standards to see if these orphaned applications can be covered by other specifications. Hydraulic fluids are already covered with proper viscosity grades. For general purpose products, users will have to search the product lines to find suitable substitutes.
(please continue to part 2)
