In recent years, the number of complaints and the severity of premature diesel fuel filter plugging have increased dramatically in the U.S. and Europe. These instances are often accompanied by longer start up times, poor drivability, and increased maintenance across different fuel filter applications. The rise in these instances of filter plugging is closely associated with the increasing prevalence of high pressure common rail (HPCR) fuel systems and the growing usage of biodiesel. Smaller pore size restrictions for fuel filters due to tighter clearances in HPCR injectors, coupled with contaminants from biodiesel and carboxylate salts in fuel, have been identified as accelerants of diesel fuel filter plugging.Testing protocols will be reported that can be used to screen contaminant-doped B10 fuels (10% FAME biodiesel in ULSD) to determine their propensity to plug fuel filters. Fuels were evaluated using bench-top filtration testing equipment to determine their filter blocking tendency (FBT) values. Three biodiesel related contaminants were investigated: saturated monoglycerides, sterol glucosides, and carboxylate salts.Test results will show that the specific feedstock of biodiesel - from used cooking oil to coconut oil - can alter the filterability of biodiesel-containing fuels. The same contaminant level may or may not cause filter blocking depending on the biodiesel feedstock. Additionally, the treatment of contaminant-doped fuels with commercially available deposit control additives (DCAs) will be shown to prevent or mitigate diesel fuel filter blocking.Important parameters for test fuel preparation will also be highlighted that could prove useful for internal diesel injector deposit (IDID) engine test development.