Smokey Engine

That probably won't be causing your problem. It is more likely the rings are gummed up with crud after 15 years. I would first try a dose of CEM oil flushing. I use it in my 1HZ engine always. I just use the stuff, I don't sell it so I am impartial.
After 15 years there will be a build up of crud all through the engine and the oil flushing additive will remove it but it may take two oil changes over a couple of months to get it all. The new oil will then stay oil colour for a couple of thousand kms instead of being black before you have finished checking for leaks. Good luck.
Ian

What colour is the smoke? How many klms?

Try the suggested options,CEM and the like. if it has been well serviced 500k is possible. i do know someone who's 2800 rodeo has done just that.

When did you last get your injectors serviced?

When did you last get your injectors serviced?

I had a MU, similar/same engine.
It smoked when warm and that was caused by a clapped out EGR valve.
The local deisel mechanic stuck blocking ball bearings in the vacuum lines to it, and that ended the smoke problems.
Apparently illegal, but that's a personal choice.
Probably not your problem but for the sake of 10 cents and a minutes time, may be worth trying before spending on injector etc..
Cheers

x2 on the CEM additives. also try their AW10[ I think thats it] after a few oil flushes. Their products worked well in my 80 series. Bob

Thanks to everyone who responded.
I will try the CEM engine flush first and report back. :)
Thanks again.
Clayton