Question not directed at me but I'll answer it...
I've tried a few different additives over the years. Only 1 has given me any noticeable improvement. It reduces soot dramatically, like 75% less soot in the oil analysis. I can see it on the dipstick when I check my oil, it doesn't get pitch black anymore and it takes around 5K miles before it even starts to get dark. My last analysis on my 2.8 duramax only had 0.1% soot in 8k miles. I'm overdue for an oil change in my '03 Golf and I'll have another data point when that sample gets analyzed but it had the same effect on that car. The oil is dark, but isn't pitch black and it has 11k miles of mixed driving on it. I'm sure the soot % will be low on that sample as well.
I can only assume there is enhanced combustion occurring because of the additive which is the cause of the soot reduction. Also noticed a ~ 2% increase in avg. MPG since using it, however the 2.8 is also new so the increase could be due to engine break in as well.
TL;DR Some diesel additives work and others do not.