My brother's old E28 520 is leaking oil past the front camshaft oil seal following replacement of a blown cylinder head gasket - and head planing. The seal itself was replaced on the head rebuild - and has been done again. It starts dripping about 10 minutes after a cold start and rapidly becomes a torrent. The engine runs perfectly otherwise.
He's certain the breather system is clear. It didn't do this before the head gasket failure - so is there anything associated that could cause it?