The dealer wants to do a fuel system cleaning that would clean the injectors. They say that it is different from the stuff you just dump in the tank. How so? and is it more effective? Is the the stuff I put in the tank effective at all? To what degree?
Fuel System Cleaning on 2007 Toyota 4Runner
The fuel injector cleaner used for a "fuel system cleaning" is more concentrated than what you would put in your fuel tank. What you are putting in your fuel tank is very effective as preventive maintenance. Occasionally adding fuel injector cleaner to your fuel tank is a good way to keep deposits from building up on the injectors and intake valves. If your 2007 Toyota 4Runner is running well I would see no need to pay for a "fuel system cleaning".