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Fuel additives to clean gas engine?

There are many fuel additives like STP and or some very expensive ones on the market to add to your gas tank to help clean the tank and engine and so called help the engine run better. Do they really work or is this a waste of money and also if they do work what is the best one to buy?

If you’re not using brand-name fuel, it’s not a bad thing to add a bottle of Techron every 3,000 miles or so. Put it in before filling the tank.

Most top tier gasolines already have the additives to keep your engine clean. I am not a big fan of any automotive additives but Techron seems to be a favorite on this forum.

I run can can of SeaFoam or Techron through my tanks about once a year. I have no earthly idea whether or not it does any good for the car but it makes me feel good.

However, if I have some kind of an actual problem - like a rough idle or missing or whatever - I find the problem and fix it. I don’t try to find a miracle in a bottle.

I add a bottle of Chevron Techron or Seafoam to my cars about once a year as preventive maintenance. I’ve noticed an improvement in idle quality on my older vehicles, a 2000 Blazer and a 93 Caprice.

Ed B.

Do they really work?

Sure they do, they make money to those who make and sell it. They might even help your car, but few cars ever need it as modern fuels have enough additives for almost all situations.

I also put in Techron once a year.
And I have seen it improve idle quality.

Depends on which ones you are talking about.

Some are just bottles of alcohol, and put water in suspension.
Others contain detergents, which then clean carbon in the combustion chamber, on the piston rings, and valves.

I remember back in Dec '98, I had to move from Denver to NYC, and had rented a Ryder rental truck. It was only 2 years old, but had a bunch of miles on it, and was having an idle issue, and was sluggish. So I tossed 2 full bottles of Techron Complete Fuel System cleaner into the tank, and started heading east.

Truck ran so good after the first tank of gas, I was quite shocked at how well it idled, and how smooth the throttle became. Gas mileage went up too, which helped a lot.


My 2011 Hyundai Sonata specifies either using Top Tier fuel all the time or putting in a bottle of approved fuel additive at every oil change, so apparently the engineers at Hyundai think it’s good for something. Curious to know if anyone else out there owns a direct-injection engine and, if so, whether there is a similar advisement in that person’s owner’s manual. BTW, when I did the math, it was pretty much a wash between using expensive top-tier fuel at every fill versus using a bottle of Techron at every oil change.