I've heard of Seafoam, but have never used it. I would personally recommend against using it, and only go with what the manual recommends - Techron every 7500 miles. Document when you put it in (or have the dealer do it), so you can prove that you did it if a warranty claim ever comes up.
If they figure out that you used something other than what is the service schedule calls for, then they could potentially deny a warranty claim.
Hmm... I'll need to ask my dealer about this. The only thing that worries me is that everyone at my dealer (or any local dealer) seems pretty freeking clueless about pretty much everything you ask them.
Using an additive shouldn't be necessary is using a Top Tier gasoline (Top Tier Gasoline). When I've used an additive I've been very happy with the performance of the STP Multipurpose motor treatment (Motor Treatment by STP® | Multipurpose Motor Treatment). Seems to clean just as well and maybe better and is also better for stabilizing fuel for storage IMHO.
All well and good, but for me, I'm sticking with what the manual says. If I have a problem with the engine, I don't want to get in a prolonged argument with the service manager about how I used Top Tier gasoline (will they ask me to prove it?) If I show them my service record where I used Techron, they can't argue with me. Money well spent for me.
Don't waste your money on gas treatments. JUST RUN TOP TIER GAS. If you download the gasbuddy.com App it will tell you the stations that pump top tier fuel in your area. You will be surprised. This is not a gimmick. Read up on top tier. Top Tier Gasoline