Is an Air Oil Separator just a Band-aid?

Air-Oil Separator Vs. Catch Can Part 5 - What problem does an Air Oil Separator really solve?

I went back and looked, and the last installment in the AOS Vs. Catch Can series was published in February of 2018, almost 3 years ago. It has been too long since we did more work in this direction. If you watched the Question of the Week that we put out a few weeks ago about the AOS Vs. Catch Can, I mention in there that I ended up having an issue with the drain hose of the Radium AOS that I was running, and that was the inspiration to put together a new installment in this series.

Installing an Air Oil Separator on a Subaru with a Top-Mount intercooler is tricky to say the least, especially if you are trying to drain to the top of the block, just under the intercooler piping. And that is where my issue developed.

In looking at the issue, and thinking about the best way to address it, I decided to remove the AOS all together, and go back to basics with a Radium Dual Catch Can. And it should also be said that this was all done before the 3MI AOS drain hose was available, which would have been another great option, other than the fact that it is not compatible with the Radium AOS.

Going back to the beginning in this way got me thinking about how an air oil separator is supposed to work in general.

So far, the Radium Dual Catch can, hooked up to keep the factory PCV circuits intact, has worked really well. I have a goal this year to get back to the track a few times to work on a couple of things with the WRX, which should be a great opportunity to do more testing with this.

Thanks for watching, and Stay Tuned!

- Jon Cooley