I have found Injector Decarbonizer the mid size bottle is often the best value. It is a far better value than the small 3.5 or so ounce bottle. The larger one may be a better deal yet depending on where you get them.

 

I've always heard that if you're using 94 octane you don't need to use fuel injector cleaner

 

well in colorado where we get some of the worst gas in the country... it helps. 91 octane for premium... tends to be dirty too..

 

Is it common for my audi a8 to be stalling after I put seafoam in the gas tank? That's what's happening right now.

 

It depends on how much sea foam you used. I read a few posts that tell you to use the entire can but I'm a bit wary of that and it opted for the sea foam procedure that involved injecting it into the intake manifold via a vacuum line as opposed to dumping an entire can of it into the gas tank.

Now one thing you didn't mention is wether or not you used the seafoam with a FULL tank of gas or not. If you did it with a half full tank then I'm not surprised the engine was stalling. It's been awhile, how is she running now?

 

Modern gasolines (since the 90's) have all been reformulated with more detergents and they burn cleaner than gasoline did in the 60's. Any of the "top tier" association's gasolines should be just fine without additives. If you want a little assurance, there's always Chevron's Techron, which is supposed to be the same detergents that they put in their (top tier) gasoline. A bottle every year can't hurt, except your wallet, but these days gasoline doesn't clog anything the way it did even in the 70's. Unless you're using real cheap gas and putting on really high miles.