Challenges in choosing the right lubricants
The right lubricants can smooth the path to higher fuel efficiency – and a lower carbon footprint. That’s well known. What isn’t as clear is how much can be gained. Today, lubricant suppliers have a better idea of how big the prize is. This knowledge is useful in determining how to bring out the greatest benefit. That’s attracting the attention of vehicle and engine makers, who are facing some daunting challenges in reducing vehicle fuel consumption and retaining reliable performance of applications.
In recent years, we have seen a rather worrying trend among independent workshops, where lubricants are selected incorrectly on the basis of viscosity grade only. This is exacerbated by outdated knowledge of lubricants or reliance on databases with outdated and incorrect recommendations. And if that is not enough, many of these workshops use only one type of oil, for cost saving purposes, for the majority of vehicles. This is especially dangerous as quite many specifications are mutually exclusive, some are meant to be used only in certain type of engines and some are even backwards incompatible.
The automotive lubricants industry is going through a period of almost unprecedented change as industry specifications and those related to specific vehicle manufacturers all increase in complexity. The automotive lubricants industry is currently run through pillar organisations such as European Automobile Manufacturers Association (ACEA), International Lubricant Specification Advisory Committee in North America (ILSAC), American Petroleum institute (API) and Japanese Automobile Manufacturers Association (JASO) which set the minimum performance for majority of finished lubricants sold globally. On top of the aforementioned there are also OEM in-house specifications which bring the highest quality and performance for lubricants. For example, there are 7 different engine oil specifications for Ford engines of which the latest WSS-M2C950-A and WSS-M2C952-A1 are mutually exclusive and backwards incompatible. The core reason for OEM to develop its own requirements for lubricants are mainly driven by environmental regulations to cut CO2 emissions and fuel consumption. Though there are many specifications for the ordinary vehicle lubricants, then oddly enough, specifications for lubricants and other fluids used in electric and hybrid vehicles have not yet been released. Another, and perhaps even more important aspect to consider is the lubricants compatibility to automotive fuels which on its own sets quite different rules for oil drain intervals in different markets.
European automotive market is extremely diverse and not just from an OEM perspective but also from vehicle type perspective as well. We have many types of passenger car lubricants where the main market is leisure vehicles of less than 3,5 tons of weight. These vehicles come in all different shapes and sizes: SUV’s, 4×4 wheel base or AWD, small city cars, saloons and ultimately they all come with a recommendation for a specific passenger car lubricant. Passenger car lubricant also find their way into a number of different light commercial vehicles (a commercial vehicle that is 3,5 metric tons of gross weight or less). The reason why they largely use a similar lubricant is because they contain the same engine families as found in passenger cars in most situations. Commercial vehicle lubricant market is slightly different because there’s a little bit more end use application (VAN’s) which use more often very specialised equipment.
Performance specifications are one of the foundations of automotive lubricant markets around the world – especially for engine oils – offering consumers a way to identify products shown to meet the requirements of their vehicles. Specifications are written around bench and engine tests. The latter are much more expensive, and the number of engine tests has ballooned as performance requirements for engine oils has become more difficult and as the number of requirements have increased. Finished lubricant can contain a large amount of different components. These will expand the different kind of performance levels depending on the application. The additive package and the performance polymers are both essential part of that final formulation. They play a key role in protecting different hardware types and ofcourse along side of that, the base oil makes up a significant proportion of the finished fluid. Base oil quality also varies significantly depending on the targets that oil companies are trying to meet. The cost in developing ACEA A/B oil together with OEM tests can rise well over 4 million euros, assuming, that all tests are passed first time. For example, only GM dexos2™ approval costs ~280 000 euros.
In Europe, automotive lubricant specifications base level is set by the ACEA and is written into the European Oil Sequences. The latest active document of these sequences is from 2016 and the key driver back then was the evolution of a modern engine, its after-treatment technologies and also environmental concern. With this publication we saw the deletion of ACEA A1/B1 category and the introduction of ACEA C5 category. As the industry has been waiting for the new update for couple of years already, the revisions to the ACEA Oil Sequences now look likely to be published in spring 2021. The rumours are, this update is expected to bring an unprecedented degree of change to the light-duty Sequences, but also heavy-duty sequences will be different. In the light-duty Sequences two categories will be removed, to make space for two new categories. ACEA A3/B3 and C1 categories will no longer be included, reflecting how the needs and markets have evolved. The legacy categories – ACEA A3/B4, A5/B5 and C2 to C5, remain as they are.
The two new categories will be introducing the long-awaited low speed pre-ignition (LSPI) performance as a key feature. In parallel, API in North America issued API SN Plus (and its update API SP) to fast track the introduction of this performance feature. The new categories will come with additional engine tests on three performance parameters new to the ACEA Oil Sequences, plus a new fuel economy test for ACEA C6. At the same time some tests will be replaced by successor tests and reintroduce a test for gasoline engine valvetrain wear. Also tighter elastomer limits and some other more minor changes will appear. The new ACEA A7/B7 is a new category building on A5/B5. The new features are protection against LSPI, a chain wear requirement to address wear concerns with gasoline direct injected engines and finally an all new turbocharger compressor cleanliness requirement as a preventative measure. The new ACEA C6 is the corresponding reduced SAPS category, built on C5, adding the same features as A7/B7, but on top of it has a new fuel economy test. ACEA C6 is considered the most important new ACEA category as it provides after-treatment compatibility and LSPI performance for the very important SAE XW-20 viscosity grades.
ACEA heavy-duty diesel lubricants have been designed to deliver a level of performance on which consumers can rely. Among the heavy-duty range, the ACEA E7 and E4 are being maintained at ACEA 2016 performance levels, while E6 and E9 categories will be upgraded to E8 and E11 respectfully, with several new tests making those a completely different performance level. Fuel economy drives the introduction of the new ACEA F8 and F11 categories with viscometric requirements that mirror those of the new API FA-4 oil specification in North America. The ACEA E8 and E11 performance applies also to the new fuel efficient ACEA F8 and F11 but with additional HTHSV requirement and soot induced wear tests. The ACEA Oil Sequences ensure fit for purpose engine oils in the marketplace. The key changes on the heavy-duty side are the upgrades to the ACEA E6 and E9 categories and the introduction of fuel economy grades. However, chances are, that the F8 and F11 categories will be postponed to next year as the test are being finalised and not yet ready.
Updates to the ACEA oil sequences ensure they reflect the needs of current hardware and improved fuel efficiency from the lubricant. Some of the new tests are „borrowed“ from the North American API Engine Oil Specifications, the new fuel economy test comes from the Japanese JASO specification and the Coordinating European Council, CEC, also contributes new and replacement tests. As can be seen, the ACEA Oil Sequences are clearly going global with a fundamental change in lubricant specifications and as these set the minimum performance level alongside OEM specifications it must be taken into account that for effective reduction of friction and wear, emissions reduction and fuel economy it is not enough to select a lubricant only based on preferred viscosity grade. There are far more to engine oils than viscosity grade alone.