Oil Pan Crack
JB Weld would be my first choice. I have used this stuff on a number of applications over the past 30 years, i.e. carbs, magnesium valve covers, aluminum items, and piping. Granted, a weld or pan replacement will definitely fix the problem, but a minor seep is an easy fix for JB weld. Just clean the area, make the mix (nice gray putty look), apply evenly. I would allow the fix to mend for at least 24 hrs.
Hope this is helpful.