It is not biodiesel that destroys the nissan 4 cyl 3 litre in the late GUs.
The engine self destructs. What a ridiculous proposition to replace their bulletproof 4.2 litre 6 with a fragile 3 litre 4. Nissan went up to 4.8 litres with their petrol engine in the patrol but lost the plot with the diesel.
Toyota went the other way from a 4.2 litre 6 to a 4.5 litre V8 (twin turbo).
Diehard nissan dieselers are just hanging on to their older 6 cylinder patrols and hoping that nissan will see sense and put a 6 in a new patrol.
Recomendations? Yes, trade it on a 2007 4.2 turbo intercooled patrol and get into biodiesel.