This is to weird, my last oil change at dealer used 5w-30, this time I'm doing the change myself with 10-40. I had been having just a little chain noise on start up/when cold, after I do a little driving it goes away. I think the weight diff. will help with the noise. Depending on your mileage you could go 5w-50 synthetic. I just dont want to take the chance on synthetic now because the car has never had it and I'm at 150k. I have used the Lucas oil stabilizer in my 2.0 AEG(burns less with this product), I dont know how I feel about it in my VR????
It doesn't really sound like you or your dealer are using the proper oil. I would suggest M1 0W40 as it is easy to get ahold of and high quality. Another easy to get, well respected oil would be German Castrol (GC) 0W30. I would not suggest adding any additional additives to any oil, much less a high quality synthetic.
Whether or not this will help with your timing chain noise is not clear... it may just be time to have them done.
Obviously you should be using the proper viscosity approved VW 502 oil. That being said the VR6 engine timing chains, guides and tensioners wear and need replacement periodicly. They become noisy before or while they are starting to wear/fail.