TLDR: For the 2.4 Turbo the F108SX is the one to use, for the 2.5 any of the F108 series can be used including F108SX, F108N, F108, etc. Fumoto specifies 18 foot pounds to torque their brass valves, stock steel plug is 33 foot pounds. I've installed many Fumoto valves without using a torque wrench and they've never leaked. Do not use a crush washer with a Fumoto - they supply a felt washer with some, and the F108SX has an o-ring - do not add extra washers.
So today I received the F108N and along with the F105N I planned to change my oil, filter, and install whichever Fumoto valve had the correct thread size.
Looking under the car, I was surprised that there wasn't more plastic undercladding. The oil pan is exposed, nestled between exhaust and sway bar. Notably it's very deep where the drain plug goes, so it's great that it's not a big flat pan. It should drain well.
14mm Drain plug, was pretty tight. For 2022+ Subaru has changed the OE drain plug to 17mm head - same thread. (NOTE - I did not have this problem but several owners have rounded their drain plugs. Only use a 6 point socket for removal) After removing it, it appears that the inside of the pan was painted while the drain plug was in. It shows what parts of the thread are actually in the pan and where it's only in the oil. The thread matches the F108 and the F108's threads are short enough that it will not cause excess oil to remain in the oil pan. We can put that concern aside.
Ok, time to install the F108N but oh no! It won't rotate! The exhaust heat shield prevents the valve body from rotating and letting me screw the whole thing in. Oh well. I'm not prepared to remove the exhaust heat shield today just for the sake of the Fumoto valve. OEM plug put back in. Will consider whether removing exhaust heat shield or trying the F108SX makes more sense at the next oil change. At least F105 in any variant is definitively ruled out no matter what specs say on the web, for the 2020 Outback 2.4 XT
OK put in the Wix 57055XP (27psi bypass valve) and new full synthetic 0w-20 SN-Plus Dexos 1 gen 2 oil in using the special funnel.
(as of 2023 the current specs are ILSAC GF-6, API SP, Dexos 1 Gen 3)
Additional notes:
Oil level was at least half a quart high from the dealer. After 675 miles, oil level doesn't appear any higher or lower.
With both engines off overnight, compared the smell of a 2009 Honda Fit's several thousand miles old oil, and the 2020 Outback's 675 mile old oil.
Both had some gasoline smell, but nothing alarming, with the Fit oil smelling more "used engine oil" smell. It was quite dark. The Outback's oil was still light brown on the dipstick. Changed it anyways for the sake of identifying the correct Fumoto valve. When in the drain pan, the Outback's oil didn't look so golden. It was surprisingly dirty looking. Oh well. Not sending in a sample for analysis. F105N has wrong thread. F108N does not fit - will not screw in.
Next step will be to buy the F108SX and try again at the end of January, or maybe consider removing exhaust heat shield to salvage the F108N. If I could screw it all the way in, it would fit. Only question would be where the valve control would end up. There's not much space there for it to be accessible unless it's in the right position. Makes the F108SX seem very promising.
So today I received the F108N and along with the F105N I planned to change my oil, filter, and install whichever Fumoto valve had the correct thread size.
Looking under the car, I was surprised that there wasn't more plastic undercladding. The oil pan is exposed, nestled between exhaust and sway bar. Notably it's very deep where the drain plug goes, so it's great that it's not a big flat pan. It should drain well.
14mm Drain plug, was pretty tight. For 2022+ Subaru has changed the OE drain plug to 17mm head - same thread. (NOTE - I did not have this problem but several owners have rounded their drain plugs. Only use a 6 point socket for removal) After removing it, it appears that the inside of the pan was painted while the drain plug was in. It shows what parts of the thread are actually in the pan and where it's only in the oil. The thread matches the F108 and the F108's threads are short enough that it will not cause excess oil to remain in the oil pan. We can put that concern aside.
Ok, time to install the F108N but oh no! It won't rotate! The exhaust heat shield prevents the valve body from rotating and letting me screw the whole thing in. Oh well. I'm not prepared to remove the exhaust heat shield today just for the sake of the Fumoto valve. OEM plug put back in. Will consider whether removing exhaust heat shield or trying the F108SX makes more sense at the next oil change. At least F105 in any variant is definitively ruled out no matter what specs say on the web, for the 2020 Outback 2.4 XT
OK put in the Wix 57055XP (27psi bypass valve) and new full synthetic 0w-20 SN-Plus Dexos 1 gen 2 oil in using the special funnel.
(as of 2023 the current specs are ILSAC GF-6, API SP, Dexos 1 Gen 3)
Additional notes:
Oil level was at least half a quart high from the dealer. After 675 miles, oil level doesn't appear any higher or lower.
With both engines off overnight, compared the smell of a 2009 Honda Fit's several thousand miles old oil, and the 2020 Outback's 675 mile old oil.
Both had some gasoline smell, but nothing alarming, with the Fit oil smelling more "used engine oil" smell. It was quite dark. The Outback's oil was still light brown on the dipstick. Changed it anyways for the sake of identifying the correct Fumoto valve. When in the drain pan, the Outback's oil didn't look so golden. It was surprisingly dirty looking. Oh well. Not sending in a sample for analysis. F105N has wrong thread. F108N does not fit - will not screw in.
Next step will be to buy the F108SX and try again at the end of January, or maybe consider removing exhaust heat shield to salvage the F108N. If I could screw it all the way in, it would fit. Only question would be where the valve control would end up. There's not much space there for it to be accessible unless it's in the right position. Makes the F108SX seem very promising.