Best of Deals Car Reviews Repair Shops Cars A-Z Radio Show

Additives for gas with ethenol

My car started running and idling rough after the latest tank of gas. The dealer said it has shown codes for all cylinders misfiring. The fix is to use more expensive gas or put in an additive of some kind to counteract moisture in the fuel. What additive is recommended?

Add a can of Seafoam to the gas tank.


Ethanol serves the same purpose as additives that remove moisture from the fuel, and you shouldn’t need such additives.

I’d wait and see what happens next time you fill the gas tank.

If you feel you should try a moisture removal additive, go to an auto parts store and select from the brands on the shelf. They all contain the same ingredient.

Thanks for your quick response

Thanks for your quick response

I don’t think Ethanol is the issue. Techron fuel system cleaner usually comes highly recommended, as does Seafoam.

I don’t think Ethanol is your problem unless your car was made before 1987 and lacks fuel injection. Old school carburetors sometimes had rubber parts that were damaged by Ethanol, but if your Avalon is fuel injected, that shouldn’t be an issue. I think the issue is more likely to be related to your ignition system. The fact that it happened after you bought gas might be a coincidence.

If this doesn’t clear up after a tank or two of gas, and a bottle or two of fuel system cleaner, I would consider replacing the spark plugs, and possibly the spark plug wires if they haven’t been replaced in a long time. If none of this fixes your problem, you might have more serious issues.

How many miles on the car?
When were the spark plugs last changed?