Treating pyrolysis oil for internal combustion engines

A pyrolysis oil treatment system for treating pyrolysis oil for being used as a fuel of an internal combustion engine (100) may comprise at least one pyrolysis oil tank (1212), at least one cleaning medium tank (1222, 1224, 1226), at least one treated pyrolysis oil tank (1250); and at least one reusable pyrolysis oil/cleaning medium mixture tank (1214). The pyrolysis oil treatment system may further comprise at least one pyrolysis oil treatment unit (1310), wherein the at least one pyrolysis oil treatment unit (1310) is fluidly connected via a first flushing valve (1388) to the at least one pyrolysis oil tank (1212) and the at least one cleaning medium tank (1222, 1224, 1226) to receive pyrolysis oil and cleaning medium respectively therefrom, and the at least one pyrolysis oil treatment unit (1310) is further fluidly connected via a second flushing valve (1390) to the at least one treated pyrolysis oil tank (1250) and to the at least one reusable pyrolysis oil/cleaning medium mixture tank (1214). Castor oil, ethanol, and a cleaning fluid/fuel comprising castor oil and ethanol may be examples of a cleaning medium.