RTV ought to fix that up just fine (silicone like gasket maker you can find anywhere, make sure it is oil resistant). Just be careful to keep it from getting in the engine and clean it up pretty before applying.ah, and do you know if it takes a gasket or new o-ring? Mine seems to be weeping a bit.
Well...The oil pressure sensor switch uses a pipe thread type fitting, so there's no gasket or o-ring.
If it's wet around the upper part of the switch, it's possible the internal diaphragm/seal has been breached and oil is seeping out between the lower metal base and the upper plastic part where they're crimped together, or at the top where the terminal comes out. This is not uncommon. If the switch is leaking, then it should be replaced. Long term, it won't get better, and the switch can either stop working (see linked thread) or, worst case, the crimp loosens and oil starts flowing out through the gap (seen that too).
(See http://www.subaruoutback.org/forums/66-problems-maintenance/35622-oil-pressure-sensor-switch-how-clicks.html for photos and explanation.)
Probably depends on the tools you have, and the clearance. It might be possible to get a deep socket over it (can't tell from the photo) or use a flex-head ratcheting wrench. It shouldn't be necessary to do too much turning with the wrench to loosen the switch enough to remove by hand.Do I have to remove the alternator?
Every EJ engine that I know of uses an adapter. The holes into the oil galley are rather large and most sending units are 1/8". I really doubt Subaru was concerned with the oil pressure switch taking five more minutes to change because you needed to pull the alternator.The "adapter" looks odd -- I don't recall seeing that in the breakdown diagrams. I wonder if that's original or was added, perhaps because the original threads had to be re-cut. Others here with the same generation engine might be able to verify this. The adapter would raise the switch higher (looks like 1/2-inch or more), bringing it closer to the alternator, and making it more difficult to remove without lifting the alternator out of the way.
You're absolutely right. I had looked at my 07 earlier and didn't see the adapter then, or in the service manual; however, I just went back to check again. The adapter is indeed there (confirmed by feel and an inspection mirror) but it's not clearly visible otherwise because of the crowding and the viewing angles. I stand corrected. Much appreciated.Every EJ engine that I know of uses an adapter. The holes into the oil galley are rather large and most sending units are 1/8". I really doubt Subaru was concerned with the oil pressure switch taking five more minutes to change because you needed to pull the alternator.