If anything this subject is interesting. I think folks that have DI engines are always going to be curious about what can help reduce the valve deposit issues. Seems all major makers have some kind of issues, how they deal with them may be different, but its an on going problem.
I do know VW and I am sure other companies do to, they have a coating on the valve neck that is supposed to help with the reduction of formation of carbon. This patent by VAG Group is on the first page of this topic. That is old news right?
Then we talk about gasoline. Many feel that gas quality or the detergents in gas make no difference due to the fuel delivery type. I disagree with this. Why? Just gut feeling I guess. I think how the EGR system and PCV systems work on these cars and how things get recirculated. I mean the burn rate of the fuel in the cylinder even with DI is what 70% efficiency? So where does the remaining 30% go? It gets recirculated. I believe that those vapors can indeed help with the valve issues. May be very very slight, but I think using a top tier fuel will help in the long haul. Again, cant prove it, but in theory it makes sense.
Oil. This is a very touchy subject as is most things. Talk about Religion, politics or Oil haha and you will ALWAYS get opinions. That is what makes this website so great though. The vast knowledge and experience that everyone shares.
I do believe oil quality does indeed play a role as well. Weather you can say a group 4 or 5 oil will be better than a 3+ is so subjective. VISOM and PURE+ Technologies have taken Group 3+ products and made them SO GOOD that to say Group 4 and 5 are Superior in this day and age? I think may be a stretch.
Like anything, the sum of the parts is what makes things great. You can put a MERC badge on a Pinto, but you still have a Pinto. Know what I mean? Its what makes the oil up, the combination of all its ingredients is what makes it a great oil. Finding the one you like at the price you are willing to pay, the availability and results you are looking for, often take many trials. Everyone has their own experiences and tails to tell. What I find is great oil, is somebody's worst nightmare.
I know I have bored guys on these forums with repetitious and redundant issues, I know QP on here I have irritated him many times, haha, but I am glad people like QP and others are here. They help put you in perspective and keep things real.
So keep the info coming, post whatever info you can find on DI stuff, the AudiZone bit I think is very interesting. Keep the info coming....