Replaced Water Pump,
Join Date: Aug 2009
Location: New Zealand
Generally petrol already contain an additive 'package' of octane improvers, detergents, oxygenates (to raise the available oxygen stored within the fuel), combustion catalysist/burn rate modifiers, stabilizers, polymerizers, corrosion inhibitors, etc, etc, straight from the pump. The addtive package is engineered by the fuel companies to improve the performance of their product and are at levels that provide optimum activity with minumum unwanted by-products or performance trade-offs.
Adding extra additives not knowing what is already is in the mix isn't a great idea, but proabably won't do any harm, but will probably not do much good either. There's a point to octane improvers if the original octane rating of the fuel is too low to start with. Which either means you've put the wrong stuff in the tank, or you have modified the engine to a point where detonation (pinking) is an issue.
The only fuel additive I use is Valvoline Fuel Injector cleaner about once a year, to improve spray pattern out of the injectors by dissolving the residues formed by fuel evapourating off the injector nozzles in a hot engine at shut-off.
Darryl in New Zealand