I have been doing it in my other car every other oil change. It's a 2000 toyota solara v6.
Sea foam is totally safe if you are using it in the intake and gas, but I would be careful using it in the oil just as with any engine flush or cleaner. My friend put a little to much into his civic ex and his valve seals started leaking pretty bad. I think the only reason it tells you to put 1/3 of a bottle into the intake is that so someone doesnt accidently hydro lock their engine.
This isn't a solara....not even close.