A Bit of History

Originally, the automakers had their own oil specifications and sold their own brands. Then, about 35 years ago the American Petroleum Institute, ASTM and SAE International came up with a system for designating oil quality. This is the famous (or infamous) oil classification system now governed by ILSAC (the auto industrys lubricants committee) and API Publication 1509 and documented by ASTM D4485.

As fuel economy requirements were increased, the need for oils offering lower viscosity and friction modification became more critical. Although the best-selling grades today are still SAE 10W-30 and SAE 5W-30, automakers are beginning to call for SAE 0W-20 and SAE 0W-30 engine oils for fuel economy. Emissions controls mandate the use of engine oils that are compatible with emissions systems, notably catalytic converters. This requirement places more restrictions on antiwear and ash-containing components which are both cornerstones of engine oil formulations. Through all of these changes, overall engine oil performance has improved to match the newer engine designs.

At this stage of the game, all sides have come to a level of agreement that allows the industry to create, develop, test and approve new engine oils. The bottom line is that whatever brand of GF-4 and/or API SM oil you select, it is almost certain that it will be suitable for your vehicle.

Can We Do It for Diesel?

How do we go about creating a similar, one-size-fits-all system for diesel engine oils? First, we need to udnerstand the vehicle/engine combinations and any potential engine oil issues. The automakers prefer to sell pickups, SUVs and crossover products, which the public also prefers, so that looks like a good place to start. If a diesel engine can improve fuel economy by 25 to 35 percent, it would give the original equipment manufacturers a major incentinve to continue selling what the marketplace demands.

General Motors has developed a light-duty diesel engine that will meet all state and federal emissions requirements. Current plans are to introduce this engine in model year 2009. This engine line also fills in the gap between the smaller diesel engines GMs Opel division produces in Europe and the larger engines now used in its U.S. pickup trucks.

Ford has introduced a new 6.4-liter Power Stroke diesel that is (per Ford) the quietest and cleanest diesel ever sold in America. It is targeted for Fords popular F-Series Super Duty pickup truck line. One could also visualize it in some of the larger SUVs. While it uses Navistar engines in North America, Ford also has European operations where light-duty diesels are produced.

Chrysler hasnt announced anything yet, but it seems likely to follow suit. It currently offers Cummins engines in its pickup truck lines, and its parent, DaimlerChrysler, is one of the world leaders in diesel-powered passenger cars.

We havent mentioned the Japanese OEMs. They also have a number of diesel-powered vehicles. Their engines tend to be similar to European design, so we can assume that they can be served as well.

Which Way Oil?

We know that the engine/vehicle combinations are in place and can make a mark in the North American marketplace. Can we find a simple solution for the oil component, or is the market going to have multiple brands and quality levels?

The alphabet soup of diesel engine oil specifications starts with the API categories. Currently, API CF, CF-2, CG-4, CH-4, CI-4, CI-4 PLUS and most recently CJ-4 are all active specifications and are called for by various engine manufacturers for certain applications. Many of the major engine manufacturers, such as Volvo/Mack and Cummins, also require some more restrictive test limits on one or more of the API tests to address specific issues related to their particular engines. There are even a few which call for another test not covered by API categories. Admittedly, some of the older categories (e.g. CF and CF-2) see only limited use. However, the tests needed to qualify these oils are available, so they are considered current products.

These categories traditionally have been for commercial vehicles. However, the North American pickup truck market has made use of the smaller displacement diesel engines made by some of the heavy-duty OEMs and which specify one of the API categories.

Diesel engines built specifically for passenger cars are totally European and Japanese, which adds one or two more layers of confusion to the picture. The Association des Constructeurs Europeens dAutomobiles (ACEA) has one set of engine oil specifications for passenger cars, another set for heavy-duty diesel engines, and a third for passenger cars – gasoline and diesel alike – equipped with exhaust aftertreatment devices such as catalytic converters and diesel particulate filters.

These specifications (known as ACEA Sequences A/B, E and C, respectively) utilize European engine tests. In addition, many of the European OEMs require their own tests and/or limits. This means that,

for many European automobiles, special oil is required – no one-size-fits all. Oil marketers are understandably concerned about this, as it creates logistical, labeling, advertising and a myriad of other problems.

Physical properties of API CJ-4 and several specifications from Europe can be seen in the table on page 12. The restrictions on sulfated ash, phosphorus and sulfur (SAPS) are apparent and mean some challenges for formulators.

A Solution?

For starters, we need only to look at the gasoline engine oil saga. Publius Syrus in 42 B.C.E. said, Learn to see in anothers calamity the ills which you should avoid. Most of those involved in the struggle will agree that we dont want dej`a vu all over again. Every oil marketer and engine manufacturer wants to do the right thing. The OEMs want to make sure their engines are protected adequately. The oil marketers want to make sure their oils meet the requirements of the OEMs, and are cost effective.

The third players in this story, the additive suppliers, want to make sure that there are no as-yet-undiscovered chemistries required to meet specifications. They also want to make sure that the tests selected to demonstrate oil performance are reliable and repeatable, within the limits of accepted engine test protocols.

Engine tests are, by their nature, relatively coarse determinants of oil quality. The relative precision of engine tests cant ever achieve the level of precision of, say, a viscosity test. However, engine tests can be a satisfactory tool if reasonable criteria and test limits are selected. That requires a good basis in actual use (read field data) for the parameters being measured. Certainly wear, deposits and overall efficiency are logical criteria. It doesnt make a lot of sense to measure essentially the same criteria in multiple engine tests. Working together through technical societies, the OEMs, oil marketers and additive suppliers should be able to create a standard addressing the needs of all engines in a logical and useful way.

If you can do it with a single pass through all the tests – which is rarely possible – the current cost to qualify a new API CJ-4 engine oil product hovers around $575,000. Yikes! No one wants to spend that kind of money on an engine oil formulation if they can avoid it. Recent history has shown that every new category, gasoline or diesel, has raised the ante on test costs.

At the same time, additive suppliers and oil marketers are pursuing a market which is not growing in any appreciable manner. If the automakers and oil marketers can agree that the no new engine tests will be required, costs can be controlled and test approvals can move forward more quickly. That assumes a representative set of tests from the many available can be selected to provide adequate proof of performance.

As an approach that has merit, ILSAC and API have tentatively agreed to introduce one of the ACEA Sequence C specifications for use in North America. Using the ILSAC/Oil protocols, API has stipulated that the specification (whichever one it turns out to be) needs to be carried forward without any changes in test method or limits.

Another good way to minimize the costs of engine test programs is to create a matrix approach, allowing a basic formulation to be developed and similar oils to be approved with minimal testing. This has been advanced in API. Base oil interchange and viscosity grade read-across help, and a methodology for blanket approvals should be seriously considered. DaimlerChrysler has such a program in place for its European requirements. It has been a successful system and makes it possible to have a large number of engine oils approved and available.

The Bottom line

It looks to me that North America is ready for diesel-powered automobiles. SUVs and pickups are already in the mix for diesel technology, and passenger cars can be brought on line relatively quickly. Engine oil that protects these engines is available now but it is almost a boutique market with a special oil for every engine. That has to change in order to make the diesel a viable addition to the North American scene. The various associations and industry groups need to get to work on a plan which will introduce oils to meet the needs of the engines as soon as possible.

As with most things in this industry, it looks like some fun times are ahead.