I'm guessing that question was for me disco mike?

I bought the bg44k fuel additive/cleaner. Put it into an empty tank, then filled up. My car wasn't giving me any problems, but I figured it do no harm, only good.

 

The best time to use this type of additive is on a full tank of high octane and when you are able to get a couple hours of driving at highway speeds, while the injectors or prone to be wide open.
You should have a smoother engine idle, an extra mile per gal or so and a slight improvement in power.