the_duke

I would replace those bushings if it were my car. And as it's under warranty I would insist they be replaced.

SloopJohnB@mac.com

Make the dealer replace it. If they give you grief, ask to speak to the regional audi representative. The cracks in the UCA bushing are clearly visible.
The upside of this is that Audi replaces the entire UCA and you get new balljoints in the new UCA. The labor to remove the UCA and punch out the old bushing and press in a new one and install the rebushed UCA is more than simply removing and installing a new UCA.

SloopJohnB@mac.com

You might also consider picking up another 2 years and go to 100K miles in a further warranty.

Here's my opinion on top tier (although I use it on my port injected vehicles): I don't think it makes a significant difference with direct fuel injection. The detergents in the fuel never reach the intake valve deposits because they're injected directly into the combustion chamber. I've not seen any top tier investigations or certifications for direct injection engines. FYI, top tier started as a BMW issue where BMW actually weighted intake valves before and after a 50K mile engine test to certify intake valve deposits were acceptable. TopTier may help with combustion chamber and injector deposits.

1) deposit control on intake valves; Ineffective with direct injection.

2) deposit control on fuel injectors; Might work but I note that in hundreds of thousands of miles on port injection engines I've not had a fuel injector problem but then I haven't used Petrobras or Pemex (Mexican) fuel either!

3) deposit control on combustion chambers; One of the characteristics of Top Tier requirement. Good.

4) prevention of intake-valve sticking; again, I don't see the value with direct injection. Fuel won't hit the intake valve to inhibit intake valve deposits which are what affect sticking intake valves.

Mazda has done some research on a second set of (port) injectors to help the intake valve deposit issue, but I don't know if the system has been put on any cars. BMW's M4/3 turbo engines use a methanol port injection system that should work well with blasting off intake valve if not combustion chamber deposits.

Alex100

That's what I plan to do. I'll book an appointment with Audi and ask them to fix the issue.

I do intend to buy a "4 year/50K (additional) miles" warranty extension, just to be on the safe side.

Alex100

Alright, I got an appointment with Audi Dallas for August 11th.
Let's see what their diagnosis is.

09S5

Pictures tell a story.

Alex100

I took the car to Audi Dallas this morning. When I told them about the fact that the bushings are cracked and if they can be replaced under warranty, the service manager was kind of hesitant to say "yes", because (as he explained) they need a good reason (some kind of clear symptom) in order to proceed with an under warranty repair.
I'm not a car expert, but I do understand that if the bushings are completely torn (which would cause noise and clanking in the suspenion, the "good enough" reason they're looking for) I run the risk of damaging other parts of the suspension as well. So, ideally, I shouldn't reach the point of having clear symptoms to replace the bushings.

I also told them I hear this grinding/rattling noise from the engine bay, for about 1-2 seconds, when I cold-start the car, and it sounds like maybe something's not right in the timing chains (or the tensioners), but again he was not convinced. They'll check it out though.

Also, regarding the rough idle and the vibration through the seats that I'm feeling, his theory was the carbon build up, because maybe the previous owner wasn't using top tier fuel!!!! Really, under 50K miles and carbon buildup? When I told him that I was under the impression this was more of a V8 4.2L issue, he told me that the issue exists also in the 3.0L engine. And, of course, the cleanup is not covered by warranty. I don't know, I don't think a carbon buildup would mess with the idle only (the engine sounds and feels great when the revs are even slightly over the idle, like 1200rpms on cold-start).
Besides, my previous car (370Z) had 54K miles on it, I was using premium fuel (non top tier) and had no issues with carbon buildup. And before that one, I owned a Seat Leon 1.4TSI (when I was in Europe), which is the same engine with the VW Golf 1.4TSI (turbo), and after 40K miles no issues whatsoever. It sounds to me that the carbon buildup is the easy root cause they give you when they can't identify the real issue or they want to charge you for service labor.

Anyway, next week they'll call me after checking the car.

snagitseven

An AAA comprehensive, independent lab study of Top Tier fuels was done with various engines. It showed without dispute that the detergent requirements of Top Tier made a significant difference reducing carbon buildup. Moreover, the study showed that using Top Tier fuel in cars with carbon deposits could reduce them over time.

Study: Top Tier Gasoline Worth the Extra Price - Consumer Reports

Alex100

So, in case it is indeed carbon buildup, all I have to do is sit back and relax, and keep pumping with top tier fuel. No need for me to pay a, probably expensive, carbon buildup cleaning.

snagitseven

Well, maybe yes and maybe no. If the rough idle goes away after a few tankfuls, your deposits weren't bad enough to justify a carbon cleaning. On the other hand, if that doesn't solve it and carbon deposits are determined to be the cause, a cleaning might still be in the cards.

My wife has been using mostly non-Top Tier fuel for years on her 50K mile '02 allroad 2.7T (I was already using Shell Top Tier V-Power with my '13 A6 3.0T). Last month I noticed the idle on the allroad was fluctuating even though at normal throttle it seemed fine. After reading the study, I had her start using the Top Tier Shell V-Power Nitro+. After a few fills, the idle is smoothing out so there must be something to the study's conclusions. We'll see if it continues to hold up after a few more fills.