Actually, i may have not tested the phenolic version, but i did have the very first intercooler i made, aluminum version, on my car for a little while and it ran fine. I used an oil/air separator from a 2.3 quad 4, which is the same thing as an oil catch can. I took it off to make a phenolic version and never had the time to make one for myself unfortunately, but i have no doubt they work with no problems.