dieselV6

This is exactly what I am trying to say, the "accumulated ash mass" is just VW's / ECU's theory. In practice, actual DPF condition is OK until clogged enough to cause backpressure and related loss of performance and problems with completing regen or frequent regens. Can be well before 80g, can also be way after 80g. I stress that this is certainly the case for EU5 engines, perhaps EU6 ones have better pressure monitoring, but I doubt it. The only way to be sure would be to swap the DPF without resetting ECU, drive for a while and look at the accumulated ash mass reading sometime afterwards. On EU5 TDI, for sure the ECU would not notice new DPF and just keep increasing accumulated ash value in line with mileage / number of regens. I suspect it is the same for EU6 TDIs, but not 100% sure.

Again, you might be chasing ghosts, at least on CAYC one will for sure end up with ash mass measurement exceeding limit after enough mileage and regens even if the DPF is empty of ash altogether, it is just a calculation in the ECU that does not take into account DPF pressure measurements at all. Or in other words, if you make a 300 regens and drive 100k km, the calc could be e.g. num regens x 0.1g + num kkm * 0.3g (I pulled numbers out of thin air, just like the calc in your car's ECU) resulting in 60g ash mass "measurement" even if in reality there would be only 15g-20g ash in the DPF at that point. Conversely, if you use poor quality, ash generating oil or if the engine burns a lot of oil, you may find clogged DPF while the ECU's "ash mass measurement" shows 20g or less, as in fact quite a few people have experienced. May I ask why you are chasing after this number? Are there any other issues with the engine to even be looking at ash mass?

Not sure what the exact calc for ash loading is, but it involves both number of regens and mileage. What's the mileage on each car/engine? In any case, if there are no signs of restriction in the exhaust (power loss, increased fuel consumption, regen completion issues etc.), the large amount of "accumulated ash mass" is just imaginary, there is far less ash in the DPF in reality. It is just a number / counter in the ECU which by the way can be adapted to a smaller value with VCDS, at least on earlier engines like CAYC. I honestly think that ash number was just put there to cover backside in case of clogged DPFs over the car's life, and also to force replacing DPFs latest at a certain mileage / after certain number of regens or both. The correct way to evaluate amount of ash would be to measure and average pressure loss after completion of each regen and indicate that DPF pressure loss post regen is getting on the high side, but my guess is that given varying temperatures and gas flow, the exhaust sensors used for it are either not accurate or not reliable enough, especially after many years of use / high mileage.

DPF ash load primarily depends on mileage and the number of regens. While it is possible that on EU6 engines it is measured / derived from DPF pressure loss after regen (doubt it), at least on our 2012 Roomster's EU5 1.6TDI CAYC 105bhp engine the ash load is simply calculated and increased based on mileage and number of regens, no measurements involved. If you experience frequent regens, you will find ash load going up quickly even though there is no change in pressure readings around DPF, i.e. no actual ash.

As long as the engine / mechanicals last or are replaceable / repairable, hard to predict, so I would just protect against corrosion, do all services and replace all fluids including PS, brake and gearbox oil change (plus Haldex oil on 4WD) and afterwards enjoy driving the car, replacing worn out parts on occasion. Once corrossion is taken care of / prevented, there's still mechanical wear and tear including interior, but you can replace worn bushes, fans etc. Bear in mind your satnav will run out of updates at some point, if it has not already. My Mk1 Superb has had a visible drop in parts availability about 10 years from end of manufacturing, but I guess Octavia was made in so high numbers that there will be spare parts made for a long time. Mk1 and Mk2 Skodas in general were of better quality than later ones, including better noise reduction and better interior durability. I can certainly see it comparing the wear of our 14 year old "cheap car" Roomster to a 10 year old "family car" Mk3 Octavia vRS. In a way, it is also a curse, as due to crazy Skoda model line-up policies (no manual diesels except in basic Octavia, no varioflex seats anymore in Karoq) now would be a time to replace the Roomster or even both cars with a 3-5 year old Karoq, but I just cannot bring myself to replace a car with superior quality interior, versatility, space and range with something that admittedly looks marginally better on the outside and is a little bit faster on autobahn, but otherwise nowhere near as good value for money nor as reliable / durable / maintainable. Not to mention Mk1/Mk2 headlamps, at least projector ones, being vastly better for travel abroad at night (true flat beam, not dipped z-beam).

Zinc primer is of dark grey colour (at least high purity zinc one), zinc-aluminium primer is light grey to silver. So choice of colours is rather limited unles you coat the zinc layer with paint. Personally, I'm happy with the underside of the car being 50 shades of grey ;)

Most recent one I have used is SIMONIZ Zinc Primer Spray Paint, Weld-Through Metal Primer, but I got it at <£8 per 500ml can, not £11-£13 it seems to be sold for. Having said that, if you wait long enough, you can get several cans of zinc-alu spray from Lidl when they run it as weekly special. By far lowest cost option and good enough for everything except exhaust. For the exhaust, I have one from Wurth that is rated to 400deg C, but you need trade account with Wurth to buy it. Any pure zinc primer that explicitly says it withstands 400degC is good for exhaust, there are some on ebay, there used to be excellent Normfest Galva 97 at ECP, but nowadays stupidly expensive, so best do a search on Internet, just make sure it is rated to 400degC. You could coat cold parts with cellulose lacquer after zincing them up, that extends longevity of zinc coating quite a bit. I have a towbar box mounting plate protected in this manner. However, when the coating is damaged, you would need to sand it down and reaplly zinc / lacquer. For me, it is far simpler to just keep the bare zinc and reapply where needed every couple years. For longest lasting protection, you can put 1 layer of pure zinc and then zinc-alu on top. Zinc-alu is more resistant to wear but does not stop salt spray corrossion anywhere near as well as pure zinc.

On an old car that has not been garaged, you will find that the original coating falls off from most suspension parts without much brushing, you just lift it and it falls off, at least here in Herts that's the case. Winter salt plus constant humidity strip away coatings. On exhaust, I usually use a tough cloth (a cut off leg of old jeans trousers) to take off rust growths, then zinc the whole thing up. If more rust grows in some places, it'l get taken off and recoated next time. It is also a driveway job for me. Does not look as pretty as uniform paint, but does the job. My Roomster still has original exhaust after 14 years outside...

I use zinc spray lavishly on anything underside and around engine bay, including exhaust (note pure, high temp 400deg C resistant zinc for exhaust, cheaper zinc-alu will do for other parts). Easy to apply and easy to top up in places every couple years or so (cars not garaged). Zinc is better than other coatings in that it offers galvanic protection also of nearby exposed areas. Pinch welds / jacking points are definitely worth zincing up then painting over as visible, but for lifting using garage lift it is best to put in lift pads IMHO, I have had them on all cars. Not expensive, easy to install, double the amount of support points and save wear on pinch welds. I usually lift using a trolley jack with a wide rubber pad on a lifting point/ pinch weld, then put a jack stand under the lift pad. Of course, much easier with a garage lift. HTH.

Exactly this

Premium Ridex parts (as opposed to base range) are certainly good in so far as I have used them. I have 2 steel brake discs (zinc coated) and an airco condenser/dryer on my Mk3 Octavia vRS for some years now. Have not used any parts in their base range, so cannot comment on those. On the particular topic of zinc coated brake discs, Ridex ones were 40% price of the ECP ones at the time ....

I've bought 3 new and 1 used Skoda over the past 24 years, and have similar thoughts. Already when buying latest (used) manual diesel vRS back in 2019, I was thinking that this might be my last Skoda purchase, makes me sad because previous 3 new Skoda purchases were fantastic in almost every aspect. The Karoq used to be my go to choice for the next car right until they stopped equipping it with manual gearbox diesels and the Varioflex seating. I guess the ownership of Roomster and Mk1 Superb has built up my idea of what a good car should be, and the current Skoda offerings fly far below my level of expectations. Cutting fuel tanks and range while simultaneously making the (larger fuel tank) higher end models too wide and too long for UK daily life also did not help, all parking spots in my area are still the same size as 25 years ago and for long distance travel to Europe, the only manual diesel left in the new car range is the Octavia, with a pathetic 45l fuel tank (Mk1 Octavia vented diesel fuel tank was 64l !). I am increasingly looking towards Mazda, especially that you can get 3.3l V6 diesels in their SUVs (though automatic only) as well as a large-ish 2.5l non-turbo petrol engine mated to a manual gearbox in a much smaller car that I can still actually fit in (Mazda 3).

While I am no fan of Autodoc, if you know exactly what you want (as opposed to asking Autodoc staff), parts are cheap and of good quality and I have used them several times in the past. The trouble being that "knowing exactly what you want" means down to an exact original manufacturer's part number, not just a Skoda part number. It costs quite a bit more research on internet. Autodoc do have an add on where you pay a bit more and can return unused parts within 6 months with them paying the return shipping, so if you have doubts best to use this service. For Skoda parts when I want to get exactly what is needed, I have been using a Czech shop skoda-parts.com for many years now. Consistently very good service and parts advice providing both original Skoda parts and good quality alternatives, and when they mess up even a tiny bit, they ship replacements without fuss. I steer clear of most UK parts shops nowadays, as sadly, the prices seem to be marked up 50%+. For example, a few months ago I have actually bought 2 Lesjofors suspension springs with delivery to the UK at skoda-parts.com for the price of an identical single Lesjofors spring at e.g. GSF and Eurocarparts. HTH

All season tyres by any chance? Thread pattern does make for occasional resonance, depending on surface.

In Mk1 Octavia's fuel tank there was an NRV on the outgoing line of fuel sender, at least in a 1.9TDI110 that I used to own, so Mk2 Fabia could have one too.