Have a 1.8TDCi 56 plate. To be honest it runs like a dream, never any issues starting no matter the weather. MPG around 54-56 mainly motorway running. Serviced regularly by my brother in law, whos a mechanic as per the schedule.
I cleaned the air filter today (pipercross flat panel), and pulled up the engine cover, for a general look around, and I noticed a load of oil type stuff around No1 injector, and glow plug. I first thought the rocker cover was leaking, but I never seem to have to top up with oil, inbetween services... I got a rag, to clean it up, but then found out this was a solid mass, like sealant to be honest. Its all around the glow plug, and up to the injector, and that part of the rocker cover to the gasket level. managed to break a piece off and its completely solid like tar, but a bit brittler. The other glow plugs, and injectors are clean and dry.
photos below, but wondered if anyone had any ideas what it was. Never had an issue with the engine on this car at all really.