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Biodiesel and Engine Oil Compatibility

January 01, 2013
Jean Van Rensselar
Tip or Best Practice


Hind Abi-Akar, technical expert, Fluids Engineering, for Caterpillar and member of the EMA Lubricants Committee, addresses the issue of biodiesel and oil compatibility and its potential to complicate PC-11 adoption. She reminds that the concerns with the use of biodiesel have been well documented. Related to engine oil, the issues mainly center on the fuel dilution of engine oil and the potential impact on the oil (such as oxidation or rapid degradation, potential sludge formation, impact on piston deposits and wear). But she adds that users who follow the engine manufacturer’s biodiesel quality recommendation have not encountered significant lubricant issues.

Occasionally biodiesel has been used in off-highway applications at high blend levels reaching B100. For example, some underground mining sites use high blends of biodiesel to reduce carbonaceous emissions. Acceptable operation can be obtained through careful control of biodiesel quality and management of maintenance/oil change intervals.

She concludes, “Experience in the use of this fuel in heavy-duty engines with the latest emission technologies is still not extensive. More field experience is needed to elucidate the impacts under real-life conditions and conditions associated with various engine combustion and after-treatment technologies. At this time, we recommend continued monitoring of the impact of biodiesel on engine oils. Due to the test prioritization needed to fulfill the new engine oil category timeline, biodiesel compatibility testing seems to be a lower priority than other engine tests proposed.”

Joan Evans, Infineum industry liaison advisor, adds, “Although enhanced biodiesel compatibility is one of the issues cited for improvement in PC-11, the Task Force formed to work on this issue has decided that it will not work to proactively develop a test for biodiesel compatibility but will instead keep a ‘watching brief’ on activities in Europe.”

Evans adds, “Because biodiesel has been a larger component of the fuel mix in Europe versus North America, the activity for developing tests in this area has been European-focused. The OM646 bio test is being developed by the CEC* to test the impact of biodiesel on piston deposits and potentially sludge, although it seems unlikely that the test will be able to measure sludge. The test is also not designed to look at oxidation or corrosion.”

*The Coordinating European Council for the development of performance tests for fuels, lubricants, and other fluid.

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