High-tech engines need high performance engine oils


More power, less consumption. Carefree driving pleasure, low costs and minimum emissions. This is the minefield of increasing requirements that car manufacturers have to pick their way through. What has all this got to do with lubricants? A lot. Brennstoffspiegel + Mineralölrundschau spoke to two experts who deal with the subject every day and got the car manufacturers take on things:


Ten to fifteen years ago, lubrication was not an issue for engine developers. It was there and did its job. In the meantime, this attitude has changed completely in the light of the search for the best possible ratio between power, consumption, weight and size, taking cost pressure into consideration as well. Which is why Thomas Hickl and Jonas Leber agree, that over the past few years, vehicle manufacturing has come to consider lubricant as an active construction element, ‘the precise details of which need to be known so that they can be integrated in engine development.’


Thomas Hickl, who deals with the field of engine oil specification and approval for General Motors Global Propulsion Systems at the main Opel plant in Ruesselsheim, Germany considers the subject of lubricants from the point of view of engine hardware development. Jonas Leber, a specialist for the GM subsidiary Opel who is also based in Ruesselsheim, focuses on the chemical and physical consideration of engine and transmission oils.


The two of them work hand in hand on the optimisation of engine oils. “And it really is about continuous optimisation. The current trends show this very clearly,” said Thomas confidently. This essentially means that the demands made on lubricants are becoming more and more complex and the questions to be addressed more and more detailed. And a few practical aspects have to be considered.


Keyword ‘fuel economy’ Engines are to be more compact, quieter and more efficient. There is a lot of pressure on car manufacturers to achieve this. On the one hand, new passenger cars must not emit more than 95 grams of CO2


per kilometre on average from 2020


onwards. This corresponds to a reduction in consumption to around 4.1 litres of petrol or 3.6 litres of diesel for every 100 kilometres driven. Yet on the other hand, customers do not want to do without enjoyment and comfort while driving. Alternative drive models such as gas or electric vehicles are potential solutions, as well as conventional combustion engines with an improved design. The interaction between engine technology, power and lubricant is becoming more and more crucial. A three-cylinder turbo engine with 1.0 litre displacement and direct fuel injection now achieves the same power as a significantly larger and heavier engine just a few years ago. In addition, the use of aluminium makes the engine lighter than its predecessor. This has a lot of advantages, but it also makes greater demands on the engine oil. Less oil has to perform more. An increasing number of engines are being equipped with turbochargers, for example, and may become hot during operation. If they are switched off while very hot, oil cooking can occur. To prevent this, the oil must have high thermal resistance.


Thomas described another example using the oil circuit: “The oil circuit is being optimised in terms of flow in order to reduce loss of power. Because any superfluous generation of power always costs energy and thus fuel.” According to the engineer, oil pumps are always designed for the maximum possible load. This means that a reliable oil film is guaranteed even under the most unfavourable of operating states for the engine – at high temperature, with low viscosity oil and at low engine speed. “Even when the engine is coasting following a drive over a mountain pass with a trailer, the oil still has to reach the very last corner of the engine,” Thomas said.


Accordingly, oil pumps used to be much larger. These days, much smaller units are available, which are controlled in such a way that they can be adapted to the corresponding operating states both mechanically and electronically. Fuel economy is the basis for reducing emissions. There are two reasons for emissions test methods moving towards Real Driving Emissions (RDE). For one thing, it is important to minimise the environmental pollution caused by traffic. And for another, this method simulates customers’ everyday driving conditions better. This also has consequences for lubricant development. “Where 10W-40 grade oils used to be popular, the trend is moving towards xW-20 or even down to xW-8 oils today, depending on the specific applications; in other words to products which have lower and lower viscosity yet must not lose their lubricating properties,” said Jonas, describing his day-to-day experience.


Continued on page 10


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LUBE MAGAZINE NO.134 AUGUST 2016


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