How-To: Install Prova Air Oil Separator on 2008+ Subaru Impreza WRX STi

Purchase this Air Oil Separator directly from us HERE


Prova Air oil Separator is the fastest, most simple, and the cleanest installed unit on the market. It captures the vaporized oil coming out of the heads , allows the fumes to run through the filler neck where the oil can condense back to liquid form and drop back into the motor. This will keep the oil in your motor, instead of having it get burned. This will allow you to keep your motor cleaner, and running better, along with help prolong the life of your motor. There is a reason why many high end sports cars include air oil separators, as it helps keep the motors clean and running at optimal level.

These units can be used on Turbo and NA Subaru motors.

The total install time is about 5-10 min, and requires these things.
1) Prova Air Oil Separator
2) Razor Blade
3) Pliers or something to cut zip ties

These are all the Contents of the Prova Air/Oil Separator kit. As you can see it comes with Hose, Separator, Zip Ties, Instructions, and Plastic T’s.


We did the install on a 2008 STi. However all turbo Imprezas should be 99% the same.


Start with taking off the oil cap from the filler neck.

IMG_7971_rs .jpg

Get the Air oil separator. You can see that its a 2 piece design, having the center piece screw into the filler neck securing the outer piece of separator in place.


Tighten down the center piece hand tight, and then reinstall the oil cap.


Now move over to the PCV hose that comes from the cross over pipe on the intercooler. Pull off the hose from the metal pipe.


Now follow that hose, and you will see where it attaches to the turbo inlet hose. Pull it off from there, however be careful not to break the nipple off the inlet.


The Kit comes with 2 different size hoses. The larger ID hose is for the Turbo inlet side, for the fumes coming out of the separator. The smaller ID is from the metal pipe on top of the intercooler.


Now get the supplied smaller inside diameter hose that comes with the Prova Separator and attach it to the metal pipe that runs across the intercooler.


Once attached to the hard pipe, run it over the the separator.

IMG_7978_rs.jpgThe hose supplied is about 2X as long as you need, so get the razor and cut it to the appropriate length.


Once cut to proper length attach it to one of the nipples on the separator. The way this unit is designed, it does not matter what one is in and what one is out. Making this a very easy to use unit.


Now Get the larger hose and install it onto the turbo inlet side.


Now run it over to the separator, cut to proper length, and attach it to the separator.


After all the hoses are attached, make sure that the hoses have no kinks. If everything looks proper get the supplied zip ties and secure the hoses to keep them from moving around and to make it a clean looking install.


After you are all done. This is what you will have left over. The left over fittings are to be used if you had a NA Subaru. You will notice in the image the pre-bent hose, that is the OEM piece that you pulled off that ran from the Metal cross over pipe on top of the intercooler into the turbo inlet.


Now give it a couple days and you will start noticing that the car will start running better as it will be burning off the remaining oil that is in the intercooler, turbo inlet, and inside the intake manifold.

If you guys/gals have any questions do not hesitate to ask.



  1. afisays:

    how to install on 2011 wrx..??

  2. Christophersays:

    why did Prova discontinue this

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