I have a 2002 A6 Avant (C5) with 2.5 TDI -- mileage = 185K.

Is it safe or wise to use an additive (e.g. Diesel Extreme) as I'm seeing mixed opinions regarding this?

I did clean three injectors last year when having to replace one (driver's side) and they had a bit of carbon on them but not excessive considering the mileage (I've had the car from nearly new and they'd never been cleaned).

Would really appreciate any advice.

Regards...