My daughter came home & told me of a drip, upon cleaning well & checking drain plug, I found a small punched out crack/hole about 4" behind the drain plug and a fin or two towards driver side. What wouild cause this? I did notice approx six months ago a slight whine/growl upon acceleration only. No drip back then & I did check the fluid level & it was clean & full. 

Edited August 1, 201510 yr by bork

Either hit something or something flew up from the road and hit it. Could have been internal to. Drain it and check for more then normal metal shavings.

The hole is from inside out. When I checked fluid when hot about 2 months ago, it was still clear. (when I got the car a few years ago, changed all fluids) I'll be pulling the drain plug tomorrow.