Ive only owned the WRX 2 weeks, last week I changed the oil and filter. The filter that was on there was a Ryco Z495,I couldn't get to a Subaru outlet to buy a genuine filter so I did some research and many were saying next best option is the Ryco Z436 so I fitted that.

The Z495 Filter that was on there did not leak a drop but after fitting the smaller Z495 one it started leaking out of the O Ring on the Filter??. Ive cleaned it off twice and double checked= definitely out the Filter O Ring.

I keep hearing guys saying that sometimes folk leave the old Filter O ring in the Housing by mistake then it leaks but on mine, the filter housing HAS NO O- RING RECESS!??. It mates up to a flat surface on the Filter housing?.