Oil leaks question

[knob]

Hi,
I have standard 1996 316 which has almost suddenly started leaking oil from several places on the engine. Front crankshaft seal, around the filter housing and now from the back of the engine which looks like from the rear crankshaft oil seal. I suspected it had something to do with the emission control system as if there was too much crankcase pressure and this was forcing the oil out through any "weak" points. All the hoses seem fine , clear and no obvious splits or holes. The engine has only done 103K miles and runs perfectly !! with no apparent issues. starts first turn, pulls well for a 1.6 and no smoke from the exhaust.....
It is hard to imagine the engine is goosed, rings damaged or valve seals leaking to cause excessive back pressure.
The Haynes manual states the engine is a sealed unit with all crankcase emissions controlled through the inlet and exhaust systems and requires no maintenance other than checking the condition of the hoses etc.
I changed the oil, fully synthetic, and filter and checked and cleaned as much of the inlet system as I could but its still pissing oil out.
When running and you open the oil filler cap or pull the dipstick out the revs drop slightly but no obvious sign of excessive pressure within the engine.
Anyone any ideas ? is there a valve somewhere on the intake system that I have missed and could be blocked or any other possible causes of this ?
Any help appreciated
Thanks
Jim