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Executive Roundtable

API Groups: Fit for Purpose?

The American Petroleum Institutes five familiar base oil groups are 25 years old now. Do they still meet the industrys need to efficiently formulate and manufacture engine oils-or is it time for a tune-up? For this Executive Roundtable, projects editor Lisa Tocci invited a range of base oil suppliers, engine oil marketers, additive companies and consultants to tell readers what they would change, ahead of the next cycle of heavy-duty and passenger car engine oil upgrades. She asked,

1) Are the API Groups outdated, or are they still adequate, 25 years after they were set up?

2) If not, can they be revamped, or are there any alternatives systems to consider?

3) What specific properties should be considered to differentiate base stock Groups, beyond the sulfur, aromatics and V.I. measurements used today?

With thanks to our willing experts, here are the responses.

Step Away and Try Again

Thomas R. Smith, Vice President, Lubricant Technology, Valvoline, Lexington, Kentucky

I personally believe the current system of base oil grouping has been outdated for some time. When the API Groups were initially instituted there were clear differences between the groups, but today it is much more of a spectrum. We now have oils referred to as Group I+, Group II+ and Group III+. In many instances a Group II+ may be closer to a typical Group III than a typical Group II, yet it is included as part of a Group II slate and as such formulators are free to switch back and forth between the Group II and Group II+ cuts.

The base oil groupings no longer meet their intended purpose, which was to aid in base oil interchange. I would propose abolishing the use of base oil groups for BOI and implementing a system of interchange based solely upon base oil properties. I would also re-examine the work API undertook to develop guidelines for the interchange of base stocks within a base oil slate. This is commonly referred to as the Base Oil Intra-Slate Guidelines.

Stepping away from the API Groups and looking at which base oil properties actually impact test performance would free us up to look at properties and test methods not currently included in API Document 1509, or even currently anticipated. Test matrices to develop BOI guidelines would be designed to specifically evaluate the impact of differences in those properties believed to impact performance. This will result in more effective and accurate BOI guidelines. Whether this would increase or decrease overall testing may be hard to say, but it should assure that our test dollars are spent where they are needed and greatly reduce redundant testing.

The above responses notwithstanding, the API Groups have been a useful classification for differentiating between different types of base oils in the marketplace. It would be prudent to continue with some version of the classifications solely for this purpose.

Whats at Risk: Efficiency

Ian Atherton, Senior Marketing Manager for PCMO, Afton Chemical, Richmond, Virginia

The API Groups continue to provide a means to qualify products in an efficient way that reduces the amount of testing through read-across rules. It allows base oil marketers the ability to market and sell their base oil on a consistent quality slate to ensure end users can count on lubricant performance and quality in various applications. By producing consistent base oils classified by a Group level, program design can be streamlined for efficiency and faster delivery.

As a chemical company, we typically believe there is opportunity to use sound science and risk-based assessments to enhance any current system. We are aware that some original equipment manufacturers feel that simply measuring base oil by its physical properties is not sufficiently robust enough to judge engine oil performance. However, API Group designations should not change just because theyre old. We believe that the current approach still affords robust and meaningful basis for base oil use in the industry. Any thought of changing the current approach needs to be preceded by a thorough and transparent risk assessment of the current principles-based approach. The industry can then assess the potential for improvement and the value that we are trying to achieve versus the considerable amount of work that would be entailed in redefining the base oil group definitions and characteristics.

Careful consideration is needed to ensure that any change in the properties used to characterize and classify base oils improves the consistency of quality without bringing additional cost and complexity to specification building. For example, basing API base oil groups on molecular composition would likely result in more complicated, expensive and time-consuming lubricant development programs for new specifications. Thats not good for anyone in the industry, especially the end user.

Can We Subdivide and Conquer?

Mark Matson, Technical Sales, Calumet Specialty Products Partners, Morral, Ohio

We believe most in the industry agree that updating the API base stock groups/definitions should be considered. While the current API Groups have largely functioned as they should up to this point, the scope of base stock offerings and changes in finished engine oil performance requirements are making their use increasingly difficult. To say they need to be updated is easy, but actually redefining and expanding the groups while accounting for how that impinges on base oil interchange guidelines is the difficult part. In fact, as an indicator of the level of difficulty involved, we just spent two years attempting to update the 10 Percent Rule [allowing up to 10 percent of base oil to be interchanged without retesting a licensed formulation]. Thus, any change in this system will be a monumental undertaking.

The original purpose of categorizing base stocks into these API Groups was to provide a basis for BOI guidelines. In turn, the intent of allowing for BOI was to allow for flexibility in formulating, while ensuring no sacrifice in finished engine oil performance and without incurring the prohibitive cost of individually testing every finished oil formulation. These purposes must be preserved in any system change that is attempted. Further, since the definitions are likely to become more complex, the gain should be in simplicity of their use in the BOI guidelines. However, flexibility in formulating should theoretically not change versus the current definitions.

The foregoing said, we would support an investigation into subdividing the Group II and Group III stocks into additional groups in order to accurately describe the range of stocks currently captured by those groups. Looking forward, Group V also warrants examination.

The current parameters [sulfur, saturates, viscosity index] will still largely suffice to categorize stocks, albeit with certain caveats in the BOI guidelines. Adding process to that short list would provide an additional differentiating parameter.

Make Room for Safety, Environment

Bruce Marley, Senior Vice President, Sales &Marketing, Biosynthetic Technologies, Irvine, California

The current API base oil categories have provided industry with very good technical guidance to differentiate the types of base oils available. Looking ahead, to meet the evolving maze of performance requirements for new engine and machinery designs, the trend is toward higher quality base oils and lubricants to make fuel-efficient, long-life auto­motive and industrial oils. Additional properties beyond viscosity index, such as volatility, oxidative, thermal and hydrolytic stability should be considered to further enhance the performance matrix.

In addition, rapidly changing health, safety, security and environmental policies and regulations necessitate a differentiation based on environmental performance. This can be accomplished via a subcategory to the matrix based on biodegradability and bio content, as measured for each API Group.

Plug the Gaps in Precision

Mike Brown, Vice President of Technology,
SK Lubricants Americas, Flemington, New Jersey

We believe the current definitions for API Groups are adequate. Of the properties used to define the groups, saturates is a very important component of base stocks. The saturate types are broadly: wax, isoparaffins and cycloparaffins (aka naphthenes). Each type strongly influences engine oil properties such as viscosity, oxidation stability, deposit tendencies and sludge tendencies.

With todays high quality, virgin base stock groups, the saturates minimum of 90 mass/percent for Groups II and III base stocks should be well exceeded, at 99-plus percent. However, when reported by the only specified method (ASTM D2007), saturates recovery is typically about 97 percent. These results leave experts wondering about the missing 3 percent. To update the base stock definition, we support the use of more precise methods like ASTM D7419 to report saturate and aromatic levels. Based on HPLC (high-performance liquid chromatography), D7419 much more accurately reports 99-plus percent saturates for Group II and III base stocks. In the case of rerefined base stocks, Group II saturates may still be at the 90 percent minimum spec.

Some have suggested adding API Groups II+ and III+ to the system, but we dont believe these are needed and we dont believe the current system needs revamping. In SK Lubricants opinion, further differentiation of base stock slates is not the answer at this time. The focus is on creating ILSAC GF-6 gasoline engine oils: replacement and new engine test development, agreeing on precision limits, and allowing all to formulate products meeting the new specifications. Once the backwards-compatible GF-6A version of the specification is progressing, then GF-6B for highly fuel-efficient engine oils such as SAE 0W-16 and 0W-8 will be worked.

Are We at the Tipping Point?

Chris Locke, Executive Vice President, Marketing & Technology, Infineum UK, Abingdon, U.K.

Why have base stock groups at all, and how are they used? In essence, they allow for more timely and cost-effective testing within product approval processes, or management of active product portfolios (as when a particular base stock cut is short or available at lower cost). As such, any change to the group system needs to aid this use. To be more specific, there needs to be not just a process to separate base fluids chemically (relatively easy), but one that then correlates these changes to meaningful engine oil performance prediction.

It is important to remember the history here: At the time the API Groups were conceived, the overwhelming majority of base oil was Group I. There were essentially two Group II stocks (from Sunoco and Chevron) with saturates ranging from 90 to 98, and Groups III, IV and V were niche products. Over the following quarter-century there has been huge relative growth in both the number and sources of these latter three groups, and whilst PAO (Group IV) remains tightly defined, there are now a very wide variety of Group III and V products on the market.

My personal contention is that the Group I and II buckets continue to serve the industry well. They nominally separate out conventionally refined from more heavily hydroprocessed oils, which in turn have well-developed correlations to particular types of engine performance, such as dispersancy tests. However, the Group III, IV and V categories would all conceptually benefit from a review to decide whether a more effective classification can be defined.

The practical realities will likely make this a challenging exercise. In order to be meaningful, any new system has to be universal (i.e. apply to all additive and base stock suppliers), and has to rely on the various industry stakeholders openly sharing their internal data. Of course on a practical level any such activity is very unlikely to occur-those additive or lubricant companies who have invested in wide coverage do not want to see the entry cost of others reduced unfairly. And the very value proposition of many of the more specialized base stocks is different performance from others in the slate, so those producers would be unlikely to support such sharing.

The net outcome of all of this? Whilst logic would say the time is ripe for a more systemic look at the base stock classification system, the practical realities of doing anything meaningful over and above what already exists seem very challenging. In the meantime, addressing the underlying need for BOI rules (i.e. reducing the time and cost of approvals to a manageable level) by other means, such as scrutinizing hard the number of tests in a given category per our Time for a Time Out initiative, would seem a more accessible route to achieving the same goal.

Lets Rethink Groups III-IV-V

Brent Lok, Marketing Manager, Base Oils, Chevron Corp., Richmond, California

The current definition of API base stock groups was developed 25 years ago. At that time there were far fewer API Group II stocks available, and high V.I. base stocks that might have shaped the definition of Group III at the time are no longer available today. And synthetic implied mostly PAO or similar stock. Much has changed since then.

Base stocks with V.I. greater than 120 have rapidly proliferated as a result of emerging manufacturing processes not commercially available 25 years ago. In spite of the differences between their physical/chemical properties and the perceived performance appetites of these base stocks, they are all related to each other in a single category of API Group III; broadly defined to be similar to Group II, but with V.I. at or greater than 120. At the same time, and inconsistently when compared to the broad definition of Group III, the definition of API Group IV is too restrictive. As defined, they lead to inefficiencies in terms of speed to market and logistical complexities. The focus for change should be directed at updating Group III and Group IV categories that will result in improvements to utility and market efficiencies.

In contrast, the technical basis for existing API Group I and Group II base stock categories have served the industry well for the purpose of relating base stocks within a Group to each other. The definition of these two Groups has formed the foundation for the majority of current and past test data that has enabled market efficiencies. Because of that, definitions of Group I and II base stock categories should remain as is, especially since they would minimally impact future API performance categories and tests.

With the API CK-4/FA-4 heavy-duty engine oil categories and ACEA 2016 Oil Sequences rolled out, ILSAC GF-6 advancing to completion, and the need for more fuel-efficient lubricants on the horizon, lower-viscosity engine oils and the diverse variations of base oils required to formulate them are increasingly an area of focus and development. A call to action for the industry is to recognize the benefits and undertake the effort to update and redefine Groups III and IV, and potentially V.

Erase the Quality Fallacy

Amy Claxton, President, My Energy Consulting and Training, Hummelstown, Pennsylvania

The API Groups were defined as the industry began producing hydroprocessed base oils in addition to solvent-processed base oils. Guidelines were issued to ensure that the performance of engine oils would not be adversely affected when different base oils were used interchangeably by engine oil blenders. However, as new base oil manufacturers joined the conversation over the last 25 years, a quality seriatim developed, leading to a perceived ranking of base oil groups regardless of intended application. We also saw undefined Group II+ and Group III+ stocks push their way onto the scene, further marketing the API Groups as a kind of quality grading system.

The API Groups were never intended to be a referendum on base oil quality in non-engine-oil applications, when a consortium of oil, additive and auto companies created the categories. Yet today, Group II is widely believed to have higher viscosity index than Group I (not true). Charac­teristics prized for engine oils, like V.I. and oxidative stability, are over-favored, while those critical to industrial applications, like solubility and heavy viscosity, are underrated. And naphthenics, which are not much used in automotive engine oils, were largely ignored in the conversation and tossed into the dim limbo of Group V.

The API Groups are critical for base oil interchange and viscosity grade read-across for engine oil formulation. It would be difficult to replace the system for API engine oil licensure. Instead of replacing the categories, perhaps industry education is needed regarding the original intent of the API Groups, and why theyre an unreliable yardstick for quality in other lubricant products.

First, Do No Harm

David Wedlock, Base Oil & Lubes Consultant, DW Associates, Bunbury, U.K.

Would changes to the current API groupings improve lubricant quality-hence is there a compelling need? Probably not. Additive companies in particular, who do the lions share of development and interchange work, have been asking recently for simplification of the lube product qualification processes. But all proposals Ive seen for changes to the API Groups seem to require more granularity in base stocks definition, not less; this can only lead to more complexity in product qualification and interchange of base stocks which in all probability were equivalent.

API Groups are the basis of BOI tables but where does this interchange currently help? To a limited extent, for basic API and ACEA claims only. In modern warrantied engines there is either no BOI (factory fill) or limited BOI for service fill. Most OEMs still require their own service-fill qualification testing irrespective of BOI tables.

Currently we have viscosity index, saturates and sulfur as defining specifications for API Groups. But V.I. also tells us indirectly about boiling points (Noack volatility) and intrinsic hydrocarbon quality (antioxidant responses), while saturates tells us about the absence of the worst oxidational actors (aromatics). So why add, e.g., extra Noack or oxidation specifications? Sulfur of course is becoming less relevant as Group I is almost ignored in new lube developments, but does no harm since it also tells us indirectly about absence of nitrogen, another bad actor in base stocks.

Certainly the saturates test method, ASTM D2007, could do with an update because it is cumbersome, few actually run it and there are better methods-but the basic specification is still OK.

Both API and ATIEL have considered fundamental changes to group definitions in the past. If it were that important to change the API Group structure, it would have been updated inside the 25 years of its existence.

In summary, API got it pretty right the first time, covering all the essential bases with minimum complexity.

The Real Issue: Engine Test Overload

Brian Crichton, Director, Crichton Consulting, Pitlochry, U.K.

The system has endured the test of time as a starting point for the classification of base oils, and broadly speaking it continues to be useful for defining base oils and interchange rules for Group I and Group II. I would not mess with the Group I and II definitions.

When the Group III base oil definition was put in place there were not the variety of products and manufacturing processes as there are now, and the industry was on the early part of the performance/structure learning curve. From what is now known, it seems clear that a simple classification of saturates and V.I. is not sufficient to characterize Group III base oils with respect to the chemical and physical parameters that impact performance. Ultimately it is the chemical and physical makeup of the base stock that governs performance, as well as the additive treat rates. In the case of Group III, I would look at the type of saturates present and their impact on performance, and possibly the low-temperature properties, particularly in the presence of insolubles. As we move down in viscosity, volatility differences will also play an important part in performance.

The system might be refined to facilitate enhanced BOI for Group III, but we need to weigh the benefits. If I were looking for improvements that would benefit all industry stakeholders, I would commence with an industry initiative to achieve substantial reductions in the numbers and costs of engine tests deployed throughout the world. Once we have reduced global engine testing requirements to a sensible core we could then address the issue of Group III base oil interchange-but with a reduced core we might not need to! The industry could then more easily turn its attention to reduced cycle times and real innovation rather than understanding the appetites of an endless stream of new engine tests.

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