Oil leak on backside of motor

[Chamberpains]

You may get lucky and it seals up or at very least slows the leak down. But the thin rubber on the metal gasket my also be brittle at this point from exposure to heat and movement from that bolt being loose. What I would absolutely be terrified of is that the other bolts behind the flywheel have shaken loose too. It would be best to find a very logical explanation of how that bolt got loose. Is the other 1 loose too? Was there brackets on them that someone may have taken off at some point and they never retightened the bolt? Look for scarring in the paint to maybe justify this explanation. If not, I would seriously be worried if all those other flywheel housing bolts are loose too. you run the risk of completely loosing all your oil in the engine very rapidly and very randomly if the gasket and the rear main seal fail do to movement of the rear structure.

Maybe the ISX gods will speak up and say my concern is invalid because those bolts do happen to shake loose every now and again but I'm not holding my breath on that one.