I deal with DPFs constantly. What you posted there is incorrect.
Jetta 97 is correct.
To clarify its actually the oil additives and detergents that cause cause the ash, the base oil doesn't contribute much. Fuel ash and large micron air particles that get past the air filter contribute a small fraction.
Main ash chemical is Calcium sulfate (CaSO4) which makes up roughly 3/4 of of all ash. This is from the Calcium antiwear/detergent compounds in oil, this is why VW507 oils have lower calcium levels and higher boron compound levels.
VWs use small DPFs and they fill quickly hence why they use oil with low ash requirements.
You can use any oil you want, it's your car. Just going to fill the DPF quicker.
I know what causes ash, contrary to what you believe, all common metallic anti-wear and detergent oil additives contribute to ash formation, not just calcium sulfate.
What I posted is the ASTM and EU ash properties of Diesel and common Bio/Renewable diesel blends. How can this be incorrect? Are you saying the ASTM specifications showing that Diesel is up to 0.010% ash is false or "fake news"?
Burn 1,000 lbs of fuel (multiply by ash content %) = total ash captured in the DPF. For the fuels listed in the chart above, it is 1-10 lbs of ash per 1,000 lbs of fuel.
507 is 0.6% ash and CJ-4 is 1.0% ash. As I said before, there is no additive carryover from oil vapor through the CCV. Explain how this is significant in a vehicle that does not have an oil consumption problem? it's basically a simple math problem: 1.0% ash X (zero oil consumption) vs. 0.60% ash X (zero oil consumption). Both equal zero.