Is it advisable to install an inline fuel filter along the fuel line for my 80's merc 4 cyl ?<br />Also is it advisable to add fuel additive when the boat (and gas) sits for a few months ??<br /><br />As advertised below.<br /><br />"98 Marine Fuel System Cleaner: Cleans the fuel tank and fuel system while an engine is in operation. This cleaner increases fuel economy, removes water from the entire fuel system, helps eliminate rough idling due to gum and varnish build-up, and extends spark plug life by reducing fouling & mis-fire. It is Highly concentrated to blast carbon quickly and effectively."