Originally Posted by Bill_W
I like that test you suggested Zee.. As long as the filter is still on the engine most of the particulates that enters a filter will still be there and what little make up oil to take the sample should not compromise the test. (IMO) There are variants with your suggestion of changing the filter too.
Ideally, you would not want to add any more new oil because it would still skew the PC. Solid testing results are not achieved by changing multiple variables.
Originally Posted by Bill_W
The ISO 4548-12 is one test. If I was to sell filters that would be a test I would target to look good at. If I took UOA data tests for a living and looked at all the data received, that might direct my choice on air and oil filters for my car.
The ISO 4548-12 has been the oil filter standard used for the last 20 years, so that should say something. If there was a better test then the ISO test it would have been superseded by some other filter efficiency test method. If a filter manufacturer doesn't give any ISO test numbers then there is no way to know the filtering performance. It could be anyone's guess.