Wow, 5 diesel XJs, you must have a lot of experience with them.
Unfortuneately, you may not realise that unlike in Europe, it is very rare in America to own a diesel powered passenger vehicle. Most everything is gasoline. Diesel never became popular here. Walk into a jeep dealership youre likely to get blank expressions if you ask for diesel parts. Here, we don't depend as much on dealerships for parts or service after the warranty expires anyway, but nearly all of our XJs have the 4.0 straight 6 or 4 cylinder gasoline engines.
There are also very, very few Renault cars on the road. Renault was never popular to begin with and they abandoned the U.S. market in the late 80s, so NO Renault dealerships exist (they do have some in Mexico though).
Needless to say, finding parts is going to be a challenge, but I guess its possible to get them. Do you understand the problems with owning a diesel xj here? It would be like owning a Dodge Power Wagon pickup with a V8 in Italy. I know you have some, but it would be rare.
Thanks for sharing the advise about eating its own oil, I'm sure the diesel xj owners (there are a few of them around here) will appreciate it.