Like yourself, my 2.3JTD smokesas described. After many hours of searching and asking various garages I bought some Forte Oil Seal Conditioner and added it to my engine oil. My engine has done 17K and a lot of replies when I was asking were about the oil seals on the valve stems going brittle and loosing their elasticity.
I have covered about 1.3K since adding and the smoking is definately getting less although not away completely.
Forte can be bought online although it may be worthwhile phoning some local garages to see if they carry it in stock.
Hope this is of some help to you.
Good Luck, Jim