2006 120 Injectors - When do they get changed? If at all?

[mickburkesnr]

Hi everyone,

I bought a (new to me) 2006 Land Cruiser 120 a fortnight ago, and it's done 148,000 miles. It drives well, tappy when started from cold for a minute then runs fine afterwards. Can let some black soot out the back when accelerating hard from 2,000 rpm to 3,000 rpm - which I think is normal for a diesel of this vintage that doesn't have a DPF.

With the research I did in the run up to buying it, I kept seeing things being mentioned about injectors. The car has some service history, but nothing in the way of receipts to say whether or not injectors have been changed or what not. Now I've seen it on start up and driven it etc, there is nothing right now that says the injectors are an issue. No white smoke, no blue smoke, just the black smoke as mentioned, so they're fine. 

I've seen on different places that the injectors should be changed every 100,000 miles, given i'm at 150,000 I took it that they'll have been done already and I've got 50,000 left to save up to replace them. But today I've seen two places say that they should be changed at every 150,000 miles. Which has worried me a little now, especially as they should be considered a service item.

I'd like to know whether or not this is true? Are the injectors service items? Do they get changed at 100,000 miles or 150,000 miles? Or do I change them when they present with problems instead of changing them for the sake of changing them? For what it's worth, I've used Millers Diesel EcoMax since I've got it, whether that makes a difference to the injectors or not I don't know!