fuel additives
Fuel additives are good when used for the intended purpose. Using fuel additives with the expectation that they are a cure all wont cut it though.
Octane boosters generally do what they claim, as well as do a lot of the fuel system cleaning additives.
I dont give any creedence to the ones you see being sold at the carnival or by some hawker doing infomercials on TV.
Be advised that on octane boosters, follow the recommedations on the container. Putting too much in will serve no purpose.
They are designed to enhance octane up to a particular number, and after that, it doesnt matter how much you put in, its not going to help any.
One other caviat: If you are running say a car that requires 87 octane gas and you put 104+ in it, its doing you no good whatsoever, as you are already at the octane level your engine needs. Raising the octane severely will only cause, if anything, decreased performance, and a few less bucks in your wallet.
However, if you are running say a car with a 10.5:1 or 11.5:1 compression, and 91 or 93 octane is telling you it isnt enough with that nasty pinging noise from your engine and a temp gauge that keeps heading for the redline, a can small can of 104+ to 20 gallons may be just what you need.
If thats the situation, I would start with a full tank of gas and put in one can, and see how it does. You can always add more as needed. After the first can, I would go in half can increments. Keep a note of how much it takes with a full tank, and dispence accordingly. There is no use in overdosing your gas.
A little is good, but a lot aint always gooder.
My car, pickup, and van all have fuel injected engines. I routinely, about every 5K miles dump a can of fuel system cleaner in them. My particular favorites are called Sea Foam and Blue Lightening. These are not $1.25 bottles of distilled petroleum , but run about $3.50-$5 a can and are serious system cleaners.
As for the other fuel system and carb cleaners, I have tried STP, etc and Ill stick with these two.
Last and final offering. If you are running gasahol (gasoline with 10-15% ethanol), dont bother putting Heat or any of the socalled fuel line de-icers in it. The ethanol thats in your gas will naturally take care of and do what HEAT and those other gas line antifreezes are supposed to do. Save your $1.50 and buy another gallon ( or as close as you can get to it) of gas. (current local price for 87 & 89 octane is $.162).