Just I have seen a coincidence in raised oil and fuel levels in Skyactiv UOA tests for those that have installed a oil catch can. I drive a 2019 Miata and that is a popular install. Was thinking that the OCC was a restriction and going to be seen or just a fluke.
I am bit confused why the oil levels would increase from using a catch can. In theory, the oil levels should drop slightly since oil is being removed from the engine (unless I am misunderstanding what you are saying).
Likewise for increased fuel dilution, I do not see a connection between a catch can and increased dilution. Have you seen a specific occurrence of this?