I’ve had my tdi 200 for about 18 months. The engine shuddered to a halt recently and inspection by my mechanic has shown a black jelly like sludge covering the oil strainer in the sump. He feels that previous owners have not changed the oil very frequently. The upshot is that I need a new turbo as the lack of oil getting into the engine has very likely damaged it (there is too much play on the impeller). Just out of interest, has anyone else had this issue?

Typical tight fisted Defender owner, 5000 miles or 1 year max oil change.
Might want to take the rocker cover off and have a look under there.

I had the same thing on my 200tdi, oil was so thick it would not drain out of the sump plug on its own, I added a pint of diesel and ran the engine to thin the oil, and even then I had to draw/scrape the oil out with a large cable tie.
Previous owner had run the engine on veg oil.