the B280 is a completely different engine, peugot/renault/volvo (PRV) joint design, alloy block, etc etc, there's a 760 section on this forum with more folks who know those than here in 740/940/240 land. While i owned one (a 780 Bertone) for 6 months, it was brand new and had no service other than an oil change or two.

thaty said, oil leaks from the front of an engine can be from the camshaft seals (if it uses a timing belt), valve cover gasket, intermediate shaft seal(s), or crank seal. crank seal is down low. if that engine has timing *chain* rather than a belt, then there's oil in the chain compartment at the front of the engine, and its got seals all the way around it. also joints in any plumbing going to an external oil cooler can be a source of leaks

best way to pin down an oil leak is to completely clean the engine, using a foaming engine degreaser, then put a vial of fluorescent oil dye in the oil, drive a few miles and inspect the engine with a UV light in the dark. if you don't see the dye seeping out, drive a bit more, inspect again. some oil leaks require the engine to reach full temperature (others might actually only happen when things are cold). this dye is available at most decent auto parts stores, ask at the counter.... and you can get a very cheap UV LED flashlight from amazon or ebay, ideally get one that comes with yellow safety glasses as they can help increase the color contrast of the dye.