I know VW seems to play by their own rules, but proving an oil change and maintenance would have to be spelled out in their extended warranty. To my knowledge, no such verbiage exists. For instance, I just bought a used TDI, I dont know what type of maintenance the previous owners did. The only way that would happen is if it was logged and done ONLY at a VW garage (and even then, they don't always keep the best records -hell, my car has no record of VW doing the "Fix" on my car, I only know it was dont because of the sticker under the hood.). So I think if VW claimed anything like this, it would not be hard to fight in a court. Granted, they got high dollar lawyers and money to burn and I dont, BUT unless you jest get a pisssy VW shop that is trying to void your warranty over little crap... I think you're good. I could be wrong, but its free advice- you get what you pay for.