This part of ISO 4548 specifies tests for determining the differential pressure/flow characteristics of full-flow lubricating oil filters for internal combustion engines.
Tests are specified with oils at two viscosities, one to assess the performance of a filter with a cold oil and the other to assess its performance with an oil at a typical operating temperature.
BS 7403-1:1998 history
1998BS 7403-1:1998 Full-flow lubricating oil filters for internal combustion engines. Methods of test for differential pressure/flow characteristics