Hi,

First of all you should not have green coolant in there! Zerex G-05 only!!

Second, the main block drain is just forward of that location. It is impossible to see without using an inspection mirror (or being under the car). It is 17mm if I remember correctly. Doesn't need to be super tight but yours might be loose.

To be fair the green will make the leak easier to see, but once you find the leak flush it out and put the right stuff in!

I have never heard of anyone having a leak in that area so I am guessing it is the block drain. Go buy an inspection mirror if you don't already have one. Very handy to have.

__________________
1998 C230 330,000 miles (currently dead of second failed EIS, yours will fail too, turning you into the dealer's personal human cash machine)
1988 F150 144,000 miles (leaks all the colors of the rainbow)
Previous stars: 1981 Brava 210,000 miles, 1978 128 150,000 miles, 1977 B200 Van 175,000 miles, 1972 Vega (great, if rusty, car), 1972 Celica, 1986.5 Supra