ajg617

Slight cold start stumble in the C6. I know it won't do anything for carbon buildup on the valves but read somewhere that it may reduce carbon buildup in the upper portion of the chamber itself.

Also had misfires on start up last winter in both my C6 3.2 and C5 3.0 usually after one or the other sat for a couple of days while I drove the other. Oddly, my wife's B6 3.0 never had a problem and we gas up at the same Shell or Mobil. Even happened when the cars were garaged and led to blinking CEL on both. Happened multiple times even with the cars garaged.

Have tried Techron in both. Didn't seem to notice a difference Also tried the Audi additive - that blew a lot of gray dust out the tailpipes on the C6.

But I don't want to go through the blinking CEL issue again this winter. Get great gas mileage on the C6 - a bit less in the C5 and a little below normal for it.

TIA
AJG

uberwgn

Your best bet is to try one of the products that is drawn into the induction system way upstream of the intake valves. The two products I'm familiar with are from 3M and CRC. Application is basically the same for these two products.

FL C6.5 Avant

44K is great stuff, but of limited benefit in an FSI application. might help clean injector tips if that is a worry, but won't do anything for your lower intake plenum or the cyl head upstream from the combustion chamber.
I concur with uber' suggestion.

ajg617

Probably try the CRC. Might be worth a try on my 3.0 and 1.8T as the former's gas mileage has dropped a bit and the latter seems to have an slight miss at idle (maybe I'm just not used to the 4 cyl - haven't driven it in awhile). Both recently had timing belts done and performance seems a little sluggish on both. C6 bothers me after reading the carbon buildup threads.