Bumper to bumper synthetic oils trial goes from strength to strength17 December 2014

As the hunt for incremental gains on fuel economy continues, an ExxonMobil synthetic oils trial in Denmark has shown impressive results

SPF-Danmark – one of the largest distributors of pork products in the world – moves 15 million pigs a year and uses a mixed fleet of 145 trucks to do it, with Scania the dominant marque. Like other hauliers, this operator is keen to cut fuel costs, and had already been through obvious interventions, such as aerodynamics, driver training and tyre choice. So with the advent of Euro 6, its attention turned to oils – not only to treat these hi-tech engines with the respect they command, but also for a promised fuel bonus.

Speaking at the IRTE Conference, ExxonMobil's Danish field engineer Thorleif Bache explained that, while around half of the available fuel energy disappears as engine heat, only 35% makes its way to tractive effort – with a full 15% accounted for by friction losses. That latter component will never reduce to zero, but harnessing advances in the tribology of lubricated surfaces – specifically with fully synthetic – makes a difference, he said.

How to prove the point? ExxonMobil encouraged SPF-Danmark to trial a move from its 15W-xx mineral oil to a 5W-xx low-friction fully synthetic lube throughout the drivetrain. Bache took a Scania tractor from the SPF fleet and replaced its existing 15W-40 engine oil, 80W-90 gearbox oil and 80W-140 rear axle oil with Mobil Delvac 1 LE 5W-30, Mobilube 1 SHC 75W-90 and Mobil Delvac SGO 75W-90 respectively.

The trial period was initially set at eight months, with the vehicle covering 49,000 km in that time. The bottom line was a 3.4% improvement, but not without some important variations. Initial results in January and February 2014 showed a deterioration in performance, conceded Bache – but there was a reason. The previous year's winter had been less severe, so for the early part of the trial, the truck was working much harder to gain and maintain traction. By early March, the year-on-year fuel consumption figures had converged, and they then continued to improve, with a fuel bonus of 7% in June and July, when ambient temperatures were highest.

Encouraged by the test results, SPF-Danmark then extended its trial to five Mercedes-Benz and Volvo trucks in its fleet. Running these trucks for a full year on the same combination of fully synthetic lubes resulted in average fuel savings of 3.8%. That's a figure no fleet engineer can ignore.

Brian Tinham

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