Shedding Some Light On Expanding Oil Choices
The days of “one-size-fits-all” motor oils and lubricants are ending, as new standards like the impending ILSAC GF-6 become the norm. Motor oils today are more application-specific than they were 20 years ago, and will only get more specific over the next 20 years.
New CAFE standards, environmental requirements, and increasing consumer demands are driving changes to passenger car engine hardware, such as next-generation direct-injection turbocharged engines, which need next-generation lubricants. The proposed ILSAC GF-6 specification acknowledges that GF-5-era tests simply won’t measure up to the demands placed on modern lubricants. As a result, ILSAC GF-6 will include six new engine tests, with the only carryover from GF-5 being the Sequence VIII engine test. This represents the greatest number of new engine tests ever seen with a new specification, bringing with it a host of associated challenges, complexity, and cost.
Lubricants enable new hardware technology. This key point is often overlooked in discussions about GF-6. Today, OEMs are designing new hardware that contributes directly to environmental performance. For example, by 2019, it is projected that approximately 65% of vehicles in North America will be powered by gasoline direct injection (GDI) or turbo-GDI engines. But with these hardware advancements come trade-offs, in terms of more severe operation or greater demands on the lubricant. So technology improvements to the lubricant are needed to provide the basic function of overall system protection.
The need for lubricant technology that supports new engine hardware is driving a unique approach to formulation, one that looks beyond lower viscosity. Instead, lubricant formulators are engaged in the careful selection and balance of additive, viscosity modifier, friction modifier, and base oil.
“Every new ILSAC engine oil performance category builds on the previous one by following a need for continuous improvement, and to address new emerging performance requirement. This is no different now, except that the technical challenges, complexity of managing the scope, and anticipated costs of developing new engine oil technology are truly unprecedented,” explains Matthew Ansari, Chevron Lubricants’ technical lead for consumer engine oils.
“GF-6 will address new performance areas previously not part of an engine oil’s portfolio of protection: chain wear and a special case of pre-ignition that can be mitigated through advancements in oil quality. At the same time, GF-6 will improve on those performance attributes that GF-5 has been reliably providing: fuel economy improvement, protection against wear and deposits, and continued oil service life. And finally, GF-6 will, for the first time, address a range of viscosities that require a split in performance standard; not all GF-6 oils will offer similar performance,” adds Ansari.
Consumers expect trustworthy lubricant performance in their vehicles. Oils that comply with specific standards offer end-users the assurance that they have made the right choice. The International Lubricant Standardization and Approval Committee (ILSAC) issues GF-engine oil specifications to allow for improvements in fuel economy, emission system protection, and engine oil robustness for gasoline engines. Oils meeting the ILSAC standard are identified by a certification mark, the ILSAC starburst. ILSAC GF, along with the API S categories, represent the primary engine standards in North America.
ILSAC GF-6A and GF-6B
ILSAC GF-6 actually encompasses two potential specifications: GF-6A and GF-6B. The principal difference between the two categories of oils concerns viscosity grade and high temperature, high shear (HTHS) performance. GF-6B oils provide the same performance as GF-6A, but with the added aim of lower HTHS, to potentially deliver further fuel economy benefits. This offers the possibility of potential GF-6B oils operating at viscosity ranges of less than 0W-20, once these new viscosity grades are defined and accepted by SAE.
“In addition to defining new performance requirements for GF-6, which will necessitate the development of both new tests for new performance requirements and replacement tests for obsolete versions, the OEMs have defined the need for new lower-viscosity oils below SAE xW-20 grade, as some OEMs have developed engines capable of operating on lower viscosity fluids for improved fuel efficiency,” explains Bruce Sanford, chemical technologist, Irving Blending & Packaging. “As a result, the industry is working to establish two versions of GF-6: a category currently referenced as GF-6A for current ILSAC grades (SAE 0W-20, 5W-20, 0W-30, 5W-30 & 10W-30), and a category currently referenced as GF-6B, for lower-viscosity oils meeting SAE xW-16 specification requirements. It is anticipated that the performance tests for both categories will be the same and the performance targets in these tests will be generally comparable, but there is the provision for the likelihood that some tests may have different limits. For example, the sequence VIE fuel economy test may have tiered limits for different SAE grades.”
“While it is generally accepted that lower-viscosity oil brings an improvement in fuel economy performance, it can have a negative impact on durability. The protective oil film is less robust, or under the most extreme loading conditions, non-existent. In terms of performance requirements, this translates to a set of standards that will ensure fuel economy is improved via lower viscosity, but durability will not be compromised,” explains Jaideep Sarnaik, chemical technologist, Veedol/Automobile Solutions Americas Inc.
“Engine oil tends to shear in a running engine, and HTHS occurs in various parts like bearings, piston rings, and valve train. Proper HTHS viscosity benefits in engine wear and fuel economy. Oil should form a protective film, but at the same time it should not be too thick, result[ing] in energy loss. HTHS plays an important role in fuel economy and durability of the engine,” adds Sarnaik.
“As the engine operating environment approaches hotter and more pressurized regions, it places a higher demand on the oil for lasting comprehensive protection. This trend continues, and is consequently driving improvements in the engine oil performance category. The new GF-6 category is addressing improvements in traditional protection dimensions like deposit control, preventing wear, and resisting oil breakdown, as well as new ones like preventing chain elongation, and a specific kind of pre-ignition that can be influenced by oil’s chemistry,” explains Ansari.
“GF-6 is intended to improve upon GF-5 in traditional viscosities, and establish new standards for a new range of lower-viscosity grades. Fuel economy improvements in the traditional viscosity range are not going to be realized at a protection performance deficit. That defeats the purpose, and would not be backward-compatible. The new standards for lower viscosities will be subject to every technical scrutiny to ensure the oil as formulated will protect the vehicles planning to use that oil,” continues Ansari.
“The lower viscosities are not backward-compatible and should not be used in vehicles not designed to use those oils. Clearly, the additive components used in the design of the additive system, and selection of specific base stock and viscosity modifiers, are critical to the performance of the oil. GF-6 oils will undoubtedly incorporate new chemistry and base oil technology. Ultimately, the oil marketer is responsible for the final formulation and performance of the oil, by selecting the optimal combination of additives and base oil for the purpose. The best protection for the installer and consumer is to ensure the oil is procured from known and reputable marketers with established experience in total formulation of the finished oil,” says Ansari.
More about ILSAC GF-6A
The proposed ILSAC GF-6A specification would replace the current ILSAC GF-5 specification, represented by the starburst/certification trademark, and would provide a new performance level of engine oil for spark-ignited internal combustion engines. The final standard would have to result in a balance among these equally important needs listed below. This performance standard would provide improvements relative to ILSAC GF-5 in the following categories:
• Fuel economy and fuel economy retention
• Engine oil robustness to provide performance levels required to protect engines in the global markets
• Adjustments in physical limits to allow improved performance while maintaining overall durability performance
More specifically, beyond ILSAC GF-5 requirements, ILSAC GF-6A would incorporate:
• Increased fuel economy throughout the oil change interval. Fuel consumption remains a critical issue for automotive and oil industry customers and automotive manufacturers are facing increasingly stringent regulatory requirements.
• Enhanced oil robustness for spark-ignited internal combustion engines is required to ensure acceptable engine oil performance required for regional markets (North America, Japan, Europe, etc.) due to service requirements, fuel, environment, etc.
• Formulations that protect against the occurrence of engine oil-caused low-speed engine pre-ignition. To improve overall vehicle fuel efficiency, automotive manufacturers are planning for increased numbers of smaller displacement, boosted intake engines, which may be susceptible to LSPi.
• Provide wear protection for various engine components including timing chains, valve train components, etc., including components in Idle Stop engines, PHEV, EREV, HEV (frequent starts, starts after extended periods of downtime, etc.).
• Minimum HTHS150 of 2.6 mPa-sec
“With regard to the tests used to define GF-6, there are six new tests under development, but four of these are replacements for earlier-generation tests and so we only have two genuinely new performance requirements to consider,” explains Sanford.
Sequence IIIG replacement – will be either the GM engine test, termed the GMOD, or a new Chrysler engine test. As in previous categories, the IIIH test when selected will evaluate oxidation performance and piston deposit control. OEMs have indicated that they are looking for a performance increase relative to GF-5.
Sequence IVA replacement – Toyota is working on the development of a new valve train wear test that will be designated the IVB test. OEMs have indicated that they are looking to maintain the level of performance of GF-5 oils, but in the case of GF-6B oils this may represent a performance increase due to the lower viscosity of the oils.
Sequence VG replacement – Ford is developing a replacement for the VG sludge test that will be designated the VH. Originally Ford intended this test to also include timing chain wear, but engineers were not able to achieve the required performance discrimination and so have now opted to define the VH as simply a replacement sludge and varnish test. OEMs have indicated that they are looking for a moderate improvement in sludge and varnish control relative to GF-5 oils.
Sequence VID replacement – GM has developed the replacement fuel economy test. The test uses a new engine and has revised test conditions in an effort to improve precision, but will be broadly the same as previous tests, evaluating both fuel efficiency and fuel economy retention. OEMs have indicated that they are looking for a statistically significant improvement in fuel economy performance compared to GF-5 oils.
Timing chain wear test – Ford is developing this test to address issues that have arisen in timing chain wear in direct injection gasoline engines. The maker believes that this phenomenon is related to the production of soot particles in these engines.
LSPi – low speed pre-ignition test. Ford is developing this test to protect specific engine designs and configurations from the potentially damaging effects of pre-ignition if these engines are operated at their optimum combustion efficiency. The industry consortium formed to investigate this phenomenon did not provide definitive evidence of a lubricant contribution to pre-ignition potential, but the OEMs have continued to investigate this potential and have concluded that this is a significant risk that prevents them from achieving the optimum design efficiency of certain engine designs without potential warranty issues, and so this test will be included in both GF-6A and GF-6B. GM has developed a reliable test to be included in its new GM Dexos specification, which proves the capability and feasibility of a pre-ignition test, but the maker will not allow the industry to use this for the ILSAC category. The development of a Ford version of the test is still in its early stages.
What impact will GF-6 have on passenger car engine durability? “In general, consumers should only expect improvements with every new category. GF-6 is predominantly being developed to address emerging engine needs, but will be backward-compatible in the traditional viscosity range. It will offer improvements to past performance in both protecting consumers’ engines and preventing breakdown of the oil. Similarly, in the new lower-viscosity range there is no reason to worry that new GF-6 standards will not offer durable protection. The specific engines that will call for these lower viscosities will be specifically designed to work with the lower-viscosity characteristics of these oils. This is why lower-viscosity oils should not be used in engines requiring traditional viscosity,” explains Ansari.
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