Fuel comparison

A Purdue University study shows that there is almost no statistical performance difference in semi-trailer trucks using B20, a 20 per cent blend of biodiesel, and Number 2 ultra-low-sulphur diesel, the current standard.

'In terms of performance, reliability and maintenance costs, it was basically a wash,' said John Lumkes, the assistant professor of agricultural and biological engineering at Purdue, who led the study. 'The only differences are environmental and economic.'

The study compared two 10-vehicle truck fleets using the ultra-low-sulphur fuel and B20. Trucks used for comparisons in the year-long study had the same engines, similar miles already on them at the start and drove nearly the same number of miles over the year.

The only statistical difference related to the B20 was that it lowered the oil viscosity between maintenance intervals in engines slightly more than the ultra-low-sulphur diesel. Even so, however, Lumkes said the oil still had sufficient viscosity so as not to damage engine parts.

'They were still within the range of what is acceptable before you need an oil change,' he said.

The study followed each fleet's idle time percentage, average speed, engine load percentage and engine speed. Each pair of trucks had close to the same statistics in each category.

At the end of the study, each fleet of 10 trucks had driven more than 1.5 million miles. Differences in performance based on fuel economy, fuel test results, engine oil analysis and service and maintenance costs were considered minute. B20 cost about $0.13 (£0.08) more per gallon during that time than the ultra-low-sulphur diesel.

The Indiana Soybean Alliance provided funding for the research as well as the private company that provided the trucks.