Sounds like you need to take another sample. Let the oil runout for a few then stick simple bottle in. You may have picked up the metal at the bottom of the pan.
Change the oil, get rid of the castrol 0W-40.
I would try running Pentosin High performance 5W-40, or LUBRO-MOLY 5W-40, or AGIP(ENI) eni i-Sint MS 5W-40. Repsol Elite Evolution, All 505/502 oils.
I can send you some if needed. I also have access to Titan Fuchs GT1-C3 (which I use in my TDI) 5W-30 but I have other grades Fuchs TITAN Supersyn PLUS 5W-40, Total and others Otherwise use Mobil 1 off the shelf 5W-30 (not VW approved)
or SHELL HELIX ULTRA 5W-30 (Specifications: API SL/CF; ACEA A3/B3, A3/B4; BMW LL-01; MB approval 229.5, 226.5; VW 502.00/505.00; Renault RN0700, RN0710. Meets the requirements of API SN/CF)
I'd change the oil ASAP, use MAHLE Filter and run it again. Take another test sample. Oil should be warm, take sample from middle of oil drain, not beginning.
I have a factory filter and can get different oil to put in but to be clear, this was the first change I did myself and the car probably has 100 miles on the Castrol. The oil used in the test was from the dealership.
I take care of the other cars so had been sending the Touareg to the dealership...they've done every oil change under our ownership (10 years now) and according to the invoice, they put 5w/40 in it at the last change.
I was also very careful to take the sample from the middle of the drain. Like you suggested, I let it run for ~10 seconds before I stuck the bottle under there.
There's an Advance Auto parts by me that sells Pentosin so will grab some and do another change if you think the 0w/40 is too thin. The Castrol does specify A3/B4 and it meets the VW spec on the bottle (502 00/505 00).
Nooby, I agree on the length of the journey but not much I can do about that aside from trading cars with my wife. It's been taking this route for the last two-ish years but saw more use in prior years.
Any common causes for coolant to be mixing with oil? Guess I'll run a scan too to see if anything pops up leading to a fuel related issue since they mention that too.