Add lubrication to the mix of factors that prevents biodiesel from being used as a straight-up replacement for petrodiesel. Here's the deal: The chemical properties of biodiesel make it more likely to enter and remain in the crankcase — leading to dilution of that lifeblood in every engine's motor oil. What's more, the oxidation of biodiesel in crankcase oil creates more deposits and lead corrosion.
That's the conclusion of research engineer Gary Parsons, global OEM and industry liaison manager for Chevron Oronite LLC (which develops and markets additives for fuels and lubes), who recently penned a technical paper on the impact of biodiesel on engine lubrication in the December 2007 edition of the Chevron publication Lubrication.
According to Parsons, various bench tests as well as extensive engine performance testing and a third-party survey of fleets running trucks on biodiesel indicate that “it is imperative to develop effective and reliable performance additives and new lubricant technologies before biodiesel can be safely and confidently used at elevated levels.”
Moving beyond the lab, Parsons points out a key market paradox that may intrude on the orderly development of additive solutions. “While biodiesel use will continue to increase worldwide,” he says, “engine builders and fuel system suppliers currently restrict the use of biodiesel during warranty periods due to operational concerns.”
New additive and oil technologies may be developed to address this limitation as perceived at least by engine makers and fuel system suppliers. In the here and now, though, Parsons recommends that fleet owners “conduct used oil analysis as well as reduce drain intervals to compensate for the increased severity [of engine wear] due to biodiesel use.” He adds that it should also be used in “conjunction with properly formulated lubricant technologies and performance additives.”