Hey all,

I know many of you have seen me chasing DAM drops and wondering if it's winter fuel, if the AOS is leaking, what have you. During last weekend's trans and diff fluid change, I figured I take a look at my ETS intake and MAF.

There was a thin film of oil on the MAF cable, and the MAF wasn't fully seated. I think the MAF was seated incorrectly way back when I installed the ETS intake, because I remember the O-Ring being loose.

Of course, Subaru doesn't sell the O-Ring separately. Have to buy the whole MAF. After lots of digging online (Denso part number, to seeing what cars it's used in, to seeing if anyone had a replacement o-ring size).

Finally found the size, and it's a 28mm ID by 2mm cross-section. No parts stores sell this size. So I went online to the o-ring store. Found a Buna-N material o-ring that matches. Had to buy 25 of them, but at least I'll be set for a while. Link to the part: https://www.theoringstore.com/store/index.php?main_page=product_info&cPath=368_12_11&products_id=1926

Went to install the o-ring and clean the MAF this morning. O-ring fit like a glove, used MAF cleaner spray, and figured I'd look under the filter to see if there was oil on the velocity stack.

There was a decent film of oil on the velocity stack! I have never re-oiled the filter. Used it straight from the factory. So I cleaned that all up, reinstalled everything, and went for a drive. Nothing too aggressive, since I want the car to relearn, but AF learning was going more positive, and the car seemed more responsive and smooth.

I'm waiting for a K&N dryflow black cone filter (part number: RU-3135HBK). URL: https://www.knfilters.com/ru-3135hbk-universal-clamp-on-air-filter to avoid the oiled counterparts. I'll let y'all know how it works. The dimensions are the exact same as the filter that comes with the ETS intake.

Overall, I think it's settled that I'm not a big fan of the cotton gauze oiled air filters. If you're running speed density tuning, I'm sure you'll be fine. Note: I think the Perrin filters are a good alternative as well. Thicker oil, foam material, may even work with the ETS heat shield. But I'm not ready to go down that road, yet :)