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Hi, there,

Last night my fiance decided to be very nice and change the oil in my 2004 Subaru Forester. After accidentally draining the transmission instead of the oil pan, he then proceeded to refill the transmission...except it was actually the front differential.

We needed a large torx wrench to get the differential plug out to drain it, but of course there was no such tool to be had. And this was yesterday, a federal holiday, and after 5:00 pm to boot.

He consulted with some mechanics from his job by phone and was told that nothing bad would happen...the differential needs to be lubricated, and it was lubricated, just with four quarts too many of the wrong fluid.

It's driving fine, and he's happy to go buy the correct torx wrench so he can fix his mistake. However, he won't be able to get to it until tomorrow night at the earliest, but more likely this weekend.

Is this mistake likely to do damage to my car? Can we wait until this weekend to correct the problem, or am I better off taking it somewhere to have the differential drained and refilled?

Uh...wait...we have the oil - from the engine. Then the transmission. Then the differential. All these are different.

The front differential is how power gets transferred from the driveshaft to the axle. Its about the size of a pumpkin. I haven't seen a Subaru diff, but the ones I've seen don't have a drain. You actually have to pop the cover, drain it, get some rtv or other gasket and bolt it back up - then refill through a fill plug. But I haven't seen a diff drain plug.

Could he possibly mean the transfer case? My transfer case DOES have both a fill and drain plug. And my transfer case DOES get filled with transmission fluid. But the transfer case is often in the middle of the car - and would have 2 drive shafts coming out of it - one for the front, one for the rear.

I'm pretty confused here...and wait - if he drained the diff in the first place, whats the need for the torx wrench? So he drained the transmission, but refilled the diff? Very confused...
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