I know that the oil pan plug has a copper washer that Volvo suggests we replace every time we change the oil, does the same thing apply to the transmission plugs (for a stick)?

I ask because somewhere on my car, I have a continual leak of some kind of oil based substance. I don't know if it's the real main seal, or the transmission leaking through the poor washers, or if it's leftover from the front seals that I already replaced.

As for the transmission plugs, there seems to be substance around the plugs and the filler plug washer is deformed (I don't remember it being like that when I drained and refilled the transmission). I don't know if that's the cause of the (or a) leak.

Also, I'd like to replace the upper bolt. Does anyone know where to get one (outside of a place that sells bolts)?

Thanks in advance.