Probably the capillary tube to the oil pressure gauge is cracked or not tight. It could be someone put too much lube in the speedo cable & it's leaking out but that chance would be pretty remote. I don't know any other thing under the dash that would have oil in it.

Save a life, adopt a senior shelter pet.
The three main causes of blindness: Cataracts, Politics, Religion.
Name your dog Naked so you can walk Naked in the park.