Does anyone have a positive experience of fuel additive for diesel V8?

So many in the market thought I’d ask before I take the plunge as I’ve heard mixed reviews. 2009 Vogue TDV8 Nara Bronze
2002 Vogue V8 Zambezi Silver
1986 90 Pick up Deep Bronze Green
1978 Series III SWB Deep Bronze Green

I used 2 of these bottles of additive over a 3 month trial period and carefully monitored the DPF soot levels to see if it made any difference to the distance between active regens.

I could detect no difference whatsoever, either to the performance of the car or to soot build up rate and therefore concluded that it was not worth adding.

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