One question asked if rules for lubricant specifications should allow broader interchange of API Group III base oils. According to Petronas, 75 percent of respondents voted yes, while 25 percent said no.

The survey certainly was not scientific. There were no more than 200 people in the hall at that time, and there is no telling whether respondents constituted a fair sample of the industry. Even so, in this case, the results did reflect the overwhelming interest of the industry. Broader Group III interchangeability would, if done right, benefit most base oil suppliers and lubricant blenders, as well as consumers. But it would also be difficult.

Interchange rules are about automotive engine oils and represent an attempt to strike a balance between ensuring the quality of products designated as meeting standards, and the desire of blenders to make those products economically. Industry organizations and individual automakers write specifications that establish performance parameters for engine oils, and they require extensive testing that can cost hundreds of thousands of euros.

Approvals apply to particular formulas – specific base stocks or base stock blends combined with specific combinations of chemical additives. However, the specifications usually allow formulators to substitute a limited portion of a base stock of equal grade. Essentially these interchange rules say, The original formula can vary this much without compromising the assurance that the product satisfies performance expectations. More variation than this, and one cannot be certain without additional testing that the product still meets the specification.

Interchange rules for Group I oils are relatively flexible because the industry has many decades of experience with them and confidence about the effects of substituting one Group I for another. There is much less experience with Group IIIs, and so interchange rules for them are tighter.

Caution is appropriate when product reliability is at stake, but the potential benefits of more Group III flexibility are growing. As a practical matter, formulators cant meet the latest engine oil specs using straight Group I oils; they must use a Group I-Group III blend or straight Group II. Demand for Group III is up, therefore, and will increase in the future. Also, more Group III sources are entering the market, and base oil trade is becoming more global, so buyers could tap more sellers if rules permitted.

But writing reliable interchange rules is no easy task. For one thing, variation between Group III stocks has increased. Consider viscosity index, for example. According to the American Petroleum Institutes definition, Group IIIs must have a V.I. of at least 120. A decade ago, the V.I. of most Group IIIs on the market was no higher than the mid-120s, so the range was small. Today, some have V.I. in the upper 130s, so the range is much wider.

Then there is the issue of data availability. There still is not as much data for Group III oils, and much of what exists is owned by a few Group III suppliers that paid for many tests while obtaining product approvals. That data represents a significant investment, and it is understandable that they would prefer not to share it.

Broader yet reliable Group III interchange poses technical, strategic and economic challenges. But the potential benefits are so great – and growing – that industry groups should continue investigating ways to offer more flexibility.