Greased lightning: the nanotechnology in engine oil

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Porsche 911 GT3 sports car

Vroom vroom: replacing conventional lubricant with engine oil containing tungsten or molybdenum disulfides boosts performance. Photograph: PR

The Consumer Products Inventory lists over 1,600 products that have been identified by the manufacturer as containing nanoparticles – particles between one and 100 nanometres (between one and 100 billionths of a metre) across. Many of them are found in household products. Last month we looked at sunscreen, in February it was clothes and in January toothpaste. This month it’s the turn of engine oil.

Several types of spherical nanoparticles are already being added to engine oil; including nanodiamonds and tungsten disulfide. Acting like nano-sized ball bearings, these additives are said to be better than conventional oils at lubricating the metal surfaces that come into contact within engines.

“Application of nanoparticles in internal combustion engines has two main advantages,” says mechanical engineer Ehsan Etefaghi, based at the University of Tehran in Iran. “These are improvement of tribological [the science of interacting, moving surfaces in relative motion] properties and increase in thermal conductivity.” Minimising friction and heat build-up increases fuel efficiency and reduces wear.

The development of nanoparticles as engine oil additives is still an emerging field. None of the major oil companies is working on this, but research is under way and smaller manufacturers are starting to put nanotechnology to work.

For example the AddNano Project, funded by the European Commission, has been investigating the use of molybdenum disulfide (MoS2) nanoparticles in engine oil for widespread commercial use. Researchers are aiming to create a product that can be manufactured cost-effectively, on an industrial scale, and which avoids endangering the health of production workers or the release of harmful chemicals into the environment.

NanoMaterials produces a range of lubricants that incorporate nanoparticles of tungsten disulfide (WS2) shaped like the famous fullerene “buckyballs”. The spherical particles act as miniature ball bearings inside the engine, smoothing rough surfaces and reducing friction and heat. They also form a protective layer on the engine’s metal surfaces that minimises abrasion. NanoMaterials claims that tests have shown their WS2 particles to have better lubrication properties and thermal stability than MoS2 – the more common choice of nano-lubricant.

Competitor Millers Oils is keeping quiet about future plans for its Nanodrive engine oil, which uses particles just 5 to 10 nanometres wide. So far, it has been focussing on products for the motorsport industry – an arena in which even the slightest engine improvement matters. The company claims that replacing conventional lubricant with Nanodrive oil in a Porsche 911 race engine produced an immediate power gain of 5.6%.

Technical director Martyn Mann says that Nanodrive “boosts power and torque because less energy is being wasted through friction. It’s the cheapest power increase you can get, leading to more competitive lap times.”

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