Whining in 5th Gear?

I'm getting a pretty noticeable whining coming from 5th gear, at most any velocity. It's more noticeable at lower speeds (35-45mph), but that's probably just because of the road/air noise of higher speeds. Could this be some kind of bearing?
No whining in any other gears. Though, every now and then when it's really cold in the morning, I'll hear a screech/whine when I let out the clutch when starting in 1st. I don't hear that sound for any other gear. Could that be a pilot bearing or TOB?
Any ideas?
Note: I've got no idea if the car has an OE or aftermarket clutch - I only recently bought it.

Get under your car & check that you have enough oil in the transmission. Better yet change it. I'll be it has never been changed. Good luck I hope it isn't a bearing in the transmission singing its swan song.

1ashchuckton said:

Get under your car & check that you have enough oil in the transmission. Better yet change it. I'll be it has never been changed. Good luck I hope it isn't a bearing in the transmission singing its swan song.

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Got a recommendation for trans oil I can get at a local auto parts store? I read a lot of guys here like Motul, but I can't readily buy that where I live (have to order online).

Use oem trans fluid unless its a racecar. The motul and liquimoly perform better under high heat but they make the trans a bit less smooth before the temps warm up.

Gotcha, thanks for the tip!
Called up my local dealer and they've got bottles in stock for $28.40 a pop. I'll be changing the fluid tomorrow - hopefully that's all it is.
I'll report back.

Changed out the gear oil today with OEM stuff - the old fluid looked pretty dark, but it came out to about 2.25L, so I wasn't really running low.
I'm still hearing the 5th gear whine, but it's gotten much quieter above 40-45mph. I'll continue to keep an ear on it.