Hi Enzo, there are others on this thread with a lot more experience than me, but I'll throw in my input to start you on your quest. My engine and its accessories had many leaks. I had oil leaks that showed up on the pan bottom from: valve cover gasket, hose fitting on top of oil filter, and injection pump governor housing. The main leak was was from a poorly installed rear main seal.
To find all these, I clipped on rags at various places, cleaned leaked oil away and ran car. When rag turned up wet with oil, I had my leak.
The rear main was a pain. (I purchased my car with engine out, and PO claimed it was "rebuilt". It was, but a poor job, and once in the car, it's problems showed up.) For the rear main, the oil came dripped from the flywheel housing, the lowest spot and a bit at rear of pan. To fix, you'll have to remove the engine, then the crank and replace both halves of the rear seal. At the same time, I tore down the whole engine and replaced all the things that should have been replaced by the PO's machine shop. Back in the car, the engine runs wonderful, but I still have leaks to fix (trans and power steering box), and I'm not sure that the rear main on the engine is truly fixed.
There is no gasket for the pan, use the best sealer you can find if you remove it.
If your car did not leak before your trip, I would guess it is not leaking from the pan or rear seal. Something more simple I would hope.
Ron
