Buying a used Diesel Focus. LV

[Burntorange]

As per my other thread about VIN/ENG numbers etc, I am looking at buying a used LV focus turbo diesel.

I have noticed previously comments on forums stating buying any used Diesel is playing with fire, and a risky proposition.

The car I am looking at has done 135k km, one owner, log books partially up to date, it had the first several log book services up to about 90,000km, then nothing till 120,000km, now at 135k km it is due for it's next service I assume being a 15,000km cycle.

Rego is also running out and ready for renewal 05/10.

Pulled the dip stick, oil was black. Being at the end of 15k cycle I am not sure this is an issue, and not experienced with Diesel engines. <edit> Appears diesel engines turn the oil black very quickly. The oil was not thick and didn't appear to have any other colour to it, white/cream etc.

I guess this makes me wonder if there is something hidden I need to be worried about.

Are buying used Diesels the big risk some comment on, or is this just a carry over from past diesel cars and their issues of days gone by?