[TalkDr]

Hello, I have a 2009 CLS550 with 57,000 miles. My wife took the car out a week ago and filled the tank with a lower octane gas than the premium I normally put into it. It was Unleaded Plus so the octane rating was 88. Now the car is idling and riding a little rough. I tried to drain the tank but could only get it down to about a half tank. I then took it and filled the rest with premium gas. It has gotten a little bit better but still sputters when idling or when I press the accelerator. Since I don't drive it much it would normally take weeks for the tank to need to be filled again.

Does anyone have any ideas on what I can do to try and fix this before I have to take it to the dealership? Again, it isn't terrible or kill the engine but it is noticeable.

Thanks

 

[rudeney]

I seriously doubt the issue is with the fuel octane rating. I've occasionally run 87 octane in my CLK550 and SL550 (same engine as your CL550) with no issues. I actually had an ML320 with an M112 engine where I ran 87 octane in the summer because of a defect in its TCU code that failed to adjust for the higher oxygen "summer mix" fuel causing it to backfire and die.

 

[DopeboyMagic]

1 can of Seafoam in your gas tank

 

[260e crusier]

On my low mileage car, I use Stabil Storage in the gas. I will also put in Chevon Techron Concentrate in about once a year.