I recently attended a conference given by the head of the fuel oil experiment at CDA La Rochelle. For the past two years, they have been content with running around ten trucks without modifications at 2% "fresh" rapeseed oil. For "the continuation", they started to collect the oil of the restaurants of the city, that does not miss considering the tourism ...
http://www.civitas-initiative.net/measure_sheet.phtml?lan=fr&id=317
They carried out a pollution assessment before / after.
IFP study (?) Shows that burning oil is more harmful than burning diesel, which could explain why this fuel is not authorized in public transport, yet the biggest transport budget in the city ...
After one or two years of experimentation, the verdict is final: "cleaned" engines (found on dismantling), better combustion, less pollutants.
To the innocent question: "Who financed this IFP study", big smile: Total & co of course.
The most visible particles (black smoke) are not necessarily the most dangerous, since they are filtered through the nose. The tragedy is that the manufacturers, to make diesel / fuel oil "socially acceptable" have made efforts to make particles more and more fine, close to asbestos ...