Hi,
in the above TRANSPORT ENGINEER link the Author Brian Tinham states;
"Just as convincing is another trial, concluded earlier this year, involving ExxonMobil and agricultural haulier SPF Danmark on one of its Scania Euro 4 trucks. Ahmet Aras, marketing supervisor for ExxonMobil in Europe, explains that the existing lubricants (SAE 15W-40 engine oil, 80W-90 gear oil and 80W-140 rear axle lube) were replaced with Mobil Delvac 1 LE 5W-30 engine oil, Mobilube 1 SHC 75W-90 gear oil and Mobil Delvac SGO 75W-90 rear axle oil.
"It was fully synthetic bumper to bumper, all the way along the drivetrain, and after eight months and 49,000km, SPF's onboard telematics indicated fuel savings of 3.4%," says Aras. "For them, that's 2,000 euros per annum fuel saving. For an average European haulier running its trucks at 100,000km or more per annum, the savings would be proportionately greater."
It is interest in that in 1998 I started a similar field testing project here in OZ for extended OCIs and better fuel economy. The lubricants were mineral 15W-40, 15W-40 semi synthetic and 5W-40 synthetic. I used synthetic SAE50 gearbox lubricants and synthetic 75W-90 diff lubricants. Three suppliers were involved, this was whittled down to two - and I settled on the most successful lubricant for use in my own vehicles.
As I've noted on many occasions here on BITOG this resulted in 90kkms engines OCIs and "life time" OCs in the driveline! Fuel economy improvement overall was around 2% IIRC
All this was 17 years ago - attitude, practice and operating culture shifts take a very long time indeed
