Base oils 2013: Fuel economy drives up base oil quality

15 February 2013 09:53  [Source: ICB]

Legislation around the world is driving new engine design for both passenger vehicles and heavy duty trucks, leading to the need for new lubricant standards and the introduction of new lubricant grades. These lower viscosity lubricants must have greater thermal and oxidative stability under more stressful conditions; properties that can only be achieved through the use of high quality base oils.

In the US, regulators continue to increase, in stages, the corporate average fuel economy (Cafe) requirements for passenger cars and light trucks. The joint proposal from the US Environmental Protection Agency and the National Highway Traffic Safety Administration to reduce greenhouse gas emissions and improve fuel economy has a Cafe target of 54.4 miles per gallon (mpg) (4.32 litres/100km) for model year 2025, up 81% over the 2012 target of 30.1mpg.

 prototype engine Audi

Audi 

Newly developed engine tests for prototype ILSAC GF-6A engine oils are scheduled for the first half of 2015

The European Union, meanwhile, regulates fleet-average CO2 emissions, and passed regulations in 2009 that require passenger cars to meet a target of 95g CO2/km, down from 180g CO2/km just a few years ago, and light commercial vehicles to meet a target of 135g CO2/km, both beginning in 2020.

Japanese and South Korean manufacturers have made similar commitments. Notably, the EU regulations come with strict fiscal penalties for noncompliance that will readily top €10bn ($13.3bn) if the targets are not met.

Clearly, weight reductions, improved aerodynamics and new engine designs will have the greatest impact on fuel economy. How­ever, lubricants also play a part and will be increasingly important as smaller, often turbocharged, engines that have higher power densities and run hotter, need greater protection, according to Stephen Ames, managing director of SBA Consulting.

"There is a lot of pressure on lubricant marketers to introduce new formulations that provide greater fuel economy and are robust enough to meet the more challenging operating conditions. The development costs of these new lubricants are not a direct cost to the car manufacturer," he notes.

The way to get fuel economy with lubricants, explains Infineum manager Brian Crichton, is through viscosity reduction or friction modification with additives. Since the latter approach has been fairly well-optimised, the focus is now on lowering the viscosity, but that must be done controlling volatility, oxidation and other chemical degradation, which can lead to thickening and, consequently, reduce engine protection.

Higher viscosity index base oils are the answer (the base oil makes up about 85% of a lubricant, the remainder being additives). They not only experience a limited change in viscosity with temperature, they have a higher boiling point and have reduced volatile components, according to industry consultant David Wedlock. In addition, they tend to be resistant to oxidation and are more durable.

John Rosenbaum, a senior product development engineer with US base oil producer Chevron, adds that lubricants must be compatible with exhaust systems in cars and, more recently, trucks, particularly the catalysts, which can be poisoned by sulphur. Because the additives in lubricants always contain some sulphur, base oils with no sulphur content are preferred.

STRONG GROWTH FOR GROUP II/III

"Group II and Group III base oils best meet these requirements, with the highest quality Group III and even Group IV (polyalpha- olefins) necessary for the newest proposed, very low viscosity grade oils [see below]," says Robert Sutherland, Pennzoil technology manager at Shell Oil. The impact on the base oils market, around 50-60% of which goes to transportation lubricants, will be a continuation of the shift away from Group I.

In addition, Group II/III base oils have a cost of production advantage when associated with clean fuel hydrocracking plants, according to Ames. The combination of these factors will eventually lead to a switch from Group I to Group II in most vehicle lubricant applications, with strong growth for Group III as well, according to Alan Outhwaite, manager of base oil business development for Chevron. He expects, though, that demand for Group IV oils, which account for about 1% of base oil production capacity, will remain limited due to their high cost and limited availability.

The requirements for engine oil lubricants are formalised in standards developed largely in the US and the EU. In the US, passenger car standards are developed through joint efforts of the original equipment manufacturers (OEMs) in the sector, via the International Lubricants Standardization and Advisory Committee (ILSAC). ILSAC's latest standard, GF-6, is in development and expected to be implemented in mid-2016.

Standards for heavy duty diesel engines are developed at the request of the Engine Manufacturers Association (EMA) by API and the Diesel Engine Oil Advisory Panel. The latest specifications, temporarily designated as PC-11, are slated to take effect 1 January 2016.

Drivers for development of new specifications include the introduction of new engine/emissions system technologies to meet emissions and fuel economy regulations; the availability of new fuels, such as ultra-low sulphur diesel, bio-diesel and ethanol in gasoline; and field issues, such as wear, deposits, foaming, aeration and/or oxidation, according to Paul Basar, Lubrizol's regional business manager for heavy duty diesel in Europe and Africa.

"At one time, field issues were the main driver, but lately regulations associated with emissions and fuel economy have dominated," he states. He also notes that, in general, OEM specs tend to address specific OEM field issues unique to that OEM.

The GF-6 performance standard will address the need for greater fuel economy throughout the oil change interval, increased robustness and protection for engines in regional markets, avoidance of low-speed engine pre-ignition, and better wear protection. GF-6 is also expected to have two separate specifications; one that enables backward compatibility with older engines (cars up to 20 years old remain on the road), and one that includes a new, lower viscosity grade (SAE 0W-16 and 5W-16) designed for newer engine hardware.

"This grade will require high quality Group III with some Group IV base oils to meet the requirements for low and high-temperature performance, viscosity and thickening. In fact, it is increasingly difficult to meet even middle-of-the-road specs without using Group II in combination with some Group III base oil," observes Crichton.

A DEMAND SHIFT

Meanwhile, the need for the new PC-11 standard, according to Basar, is driven by, in addition to fuel economy legislation, the increased use of bio-diesel fuel, engine oil foaming concerns and the need for greater protection from higher engine operating temperatures, engine oil shear down and piston/liner (adhesive) wear.

Demand for heavy duty engine oils is already shifting, though, and there is growing use of lower viscosity lubricants in heavy duty applications. "While SAE 15W-40 has been the most widely used in the US, it is not a fuel economy grade, and SAE 10W-30, is becoming increasingly popular," notes Wedlock.

Ames adds that even SAE 5W-30 and 5W-40 lubricants are being considered for some ­diesel engines, which means increased use of Group III base oils. It is also important to note, according to Dan Arcy, global OEM technical manager for Shell Global Solutions, that not just legislation, but the desire of consumers to achieve higher fuel economy, is driving these changes. "Fleet owners now recognise the choice of engine lubricant can have an impact on fuel economy and are switching to lighter viscosity grades. Many engine manufacturers, in response to consumer expectations, are also now allowing SAE 10W-30."

In fact, many engine manufacturers are establishing their own lubricant specifications that go beyond the European and US specifications and which require careful selection of base oils and a complex base oil strategy, says Rosenbaum. This is placing restraints on lubricant manufacturers. One consequence of tighter and demanding specifications is a reduced scope for innovation.

Specifications often contain parameters that were introduced to meet historical needs. These parameters reduce formulation freedom and restrict options targeted at ultra-strong performance, perhaps associated with enhanced fuel economy or engine cleanliness.

Shell's technology manager for innovation, Robert Mainwaring encourages an alternative view, where the OEMs and lubricant producers work together on new ideas, including the consideration of the lubricant as a design factor. "We have noticed that significant improvements in performance can be achieved when this approach is taken," he says. This issue is also relevant to additive suppliers. Lubrizol has responded by developing engine oil additives that, in many cases, meet multiple industry and OEM specifications, allowing broad-based claims, according to Basar.

Whether or not a new approach is adopted, Crichton expects to see a convergence of specifications globally by 2020. Arcy notes that EU and US lubricant needs already tend to be similar for specific engines and applications. The globalisation of engine manufacturing such that, regardless of where a model of engine is manufactured, it will require a similarly specified high-performing lubricant, will speed up the process.

In addition, the requirements of emissions legislation being adopted in emerging countries are catching up to mature economies, says Crichton, and thus the changes in engine know-how and lubricant needs in the next decade will occur more rapidly.

  • Cynthia Challener is a freelance journalist based in Burlington, Vermont, US. She is a regular writer for ICIS Chemical Business

Author: Cynthia Challener



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