ISO 4548-12:2017 specifies a multi-pass filtration test with continuous contaminant injection and using the online particle counting method for evaluating the performance of full-flow lubricating oil filters for internal combustion engines. The scope of this document is limited to steady state conditions and does not address fluctuations in the flow rate. The test procedure determines the contaminant capacity of a filter, its particulate removal characteristics and differential pressure. This test is intended for application to filter elements with an efficiency of less than 99 % at particle size greater than 10 μm. NOTE Several test flow loops built into one test rig, or several test rigs, would be necessary to cover the complete flow range of 2 l/min to 600 l/min.