I JB Welded a hole in my snow-plow jeep's oil pan 10 years ago and it's still holding!! LOL.
XJ ...4.0 I-6. I bought it cheap. At the time my old snow plow rig was just 'done' and I found this Jeep for $500 already with a plow. But it had a number of driveline issues (worn U-joints), broken coil springs, a number of small issues, and a hole near the bottom of the oil pan that all the oil would leak out. Since it was fall, I repaired the other drivetrain issues, and didn't have time to deal with the oil pan. I drained the oil out. Let it sit a few days with no oil while i was working on the other things (so oil wouldn't 'seep' through when I applied the JB Weld patch). When it came time to apply the patch, I hit the oil pan with an air grinder and 80 grit 3m sanding disk (not grinding wheel) ...to put some grinding marks for the JB Weld to 'bite' to. Mixed up the JB Weld ....waited a couple minutes for it to become slightly less runny, then sprayed the patch area with carb cleaner and degreased ...and immediately applied the JB weld to the side of the oil pan. I think I went over it again and applied a little more ...when it was still in the semi-soft stage.
I check it every year, and the patch still looks good. Like I say, it's been ...well, since 2010 ...so I guess that's 12 years now. I completely fixed an aluminum timing cover for a 1962 Ford with JB weld (behind the water pump) and that was in like 1992 ...and it's still holding!! Under hot coolant pressure!! LOL. If you do the job right, that stuff is amazing!