1991 560SEL - engine ran rough, now purrs like a kitten!

[qualified-merc]

The engine was missing real bad. I found a gas station that sells 91 octane ETHYLENE FREE gasoline so I filled up two jerry cans with about ten gallons. I then put an entire bottle of Gum Out All in One System Cleaner into the tank. I then took the jerry cans and filled the tank with ten gallons of 91 octane ETHYLENE FREE gasoline.


the car starts right up and purrs like a kitten! Smooth as an electric motor......


https://gumout.com/fuel-system-cleaner/all-in-one-fuel-system-cleaner-ethanol-treatment/

[Fleur]

You got lucky. Most chemical fixes do not work once you have actually noticed a problem.
Oh there is nothing wrong with using ethylene gas as long as you do not let the car sit. If you let it sit even for a day or two the gas gets watered down. So, if you are on a road trip, as long as you use high volume gas stations it makes no difference at all if you get the ethylene gas or not. But for most people who do not drive 50 miles plus a day avoid the stuff. I do that by only driving diesel cars.