There has always been a debate raging regarding when cam belts need to be changed, and I think a lot of it is driven by fear and, to an extent, greed. On the V6, the milage interval is stated as 80,000 miles and in Europe, that's it - no time interval. In the UK, somehow it came into being that all VAG engines should have their cambelts done every 4 years, though there was a big suspicion that this was due to water pumps with plastic impellors on higher revving petrol engines failing due to the bonding between the plastic impellor and the metal shaft failing.
Some manufacturers suggest 10 years or 120,000 miles, and to be honest, judging by the condition of the belt and tensioners that I took off that would seem perfectly reasonable to me as I could detect no wear in anything. The belts will age due to UV, but as it's pretty dark down there behind the covers, that's unlikely, and the most likely cause of failure is failing bearings on the tension or water pump casusing friction on the flat side of the belt.
The cam belt change on the V6 is no picnic, and in the past, I've been quoted between £600 and £1000 for the job, and this time, all up, I reckon it cost about £230 in belts, rollers, pump, thermostat etc and that was after getting a very good deal on components when the chance arose. There are no labour charges in there, and by the time the job was done, I reckon it took me about two days, but there was an awful lot of checking and double checking going on to avoid those costly " oh **** moments".
The pump timing is very important to get within spec, as many a VP44 pump has been suspected to have gone to that great scrapyard in the sky due to a botched cam belt change, as, if the static timing is too far out (as set on the elongated holes), the suspicion is that the internals of the pump have to work overtime to get the correct advance and retard and it self destructs.
Still, all done now and here's to another ten years or so of happy motoring