How important is the oil filter in a modern engine? How much different would a UOA look on an engine if it didn't have a filter installed? It seems that if the filter makes a significant difference in a UOA then comparing UOA's would be pointless unless the same filter was used and if the results are not significantly different, what's the reason for running a filter? For example, my 2004 Toyota Sequoia V8 is known for being "easy" on motor oil and I've even read that I should expect the oil color to appear nearly new up to 10,000 miles. If this is the case, can I assume that the oil particles suspended in the oil are extremely small and might not even get caught in a filter? The reason for my answer is that I am currently running M1 filters, that I believe to have the best filtration for my OCI, but is the $13 filter really making any tangible difference compared to a WIX or even an orange garbage can?