Nulon make a good product. To be honest the 3ltr engines in the ln167 Hilux are pretty good at accepting any sort of diesel injector cleaner, particularly because they are not a common rail diesel. Add a full bottle to the first tank and then regular amounts of it as you fill up. It should at least clear up a lot of black smoke and soot.

if she is starting to use a bit of engine oil, look to install an oil catch can To the crankcase and rocker cover breather. Stops a lot of oil fumes mixing with the intake which can lead to the engine “running on” and making black sludge in the intake and top end

Ive got a 07 Triton common rail, as scano mentioned i installed a catch can early after purchase to keep the manifolds clean due to there recycling system as such, some tritons were going into limp mode due to the position of sensor and the manifold blocking up.

Last service i did myself i installed a new Suction Control Valve with the fuel filter, cheap to buy online and this with the fuel injector cleaner has made a massive differance to performance and smoke.

 Yep, I always take them out and clean them up or replace them myself. But I’ve seen where people put a bit of automatic transmission fluid in the tank to clean them. Never done it myself, but it wouldn’t hurt it I wouldn’t think.

  Cant help with any 3 litre knowledge , but with my gq , its now up to 495,000kms , original engine uncracked with original fuel pump,

  original injectors replaced at 330,000kms , and self turboed by me at 440,000kms , being a old mechanical injected bus, I use a little bit of 

  lawn keepers two stroke oil it occasionaly , but that just keeps the seals in pump from drying out , from some reports.

  If I do use cleaner its usually that f10 stuff I think its called , blue stuff in clear long neck bottle , because thats one of the few that has bug/ algee killer in it

  for your tank and lines.

  Lastly I stick about 5  litres of premium unleaded in it , say once a year , on a full tank , before heading off on a long trip , doesnt hurt them and gives 

  a good old cleanout . Do some internet research if you dont trust what im saying.

 Finally I always go to a mob like filter supplies wa , in welshpool ,( cheaper by a long shot over any auto parts store), and keep a good stock of 

 fresh filter , air and fuel , at home so im more likely to change them before bigger trips etc , even if its way before manufactures stated km.

Before the turbo it pretty well averaged around 13-14 l/ per 100 , almost no matter what you did with it , since turbo its 11-13 l/per 100

which for a old square , loaded up gq with 495k on it is about as good as you will ever get., cheers.