I recently tried going over the recommended 91 Octane gasoline. The car ran great, but when I tried to start it in the morning, it sputtered bad. Just putting it out there.

 

I was running Chevron 91 with ethanol & Shell 91 (V-Power) without ethanol and both gave me a lot of problems in my C55...rotten egg smell, CEL, sputtering on cold starts & rough idles. The lower octane ignited more efficiently and when you have ethanol it is even more efficient. The fuel burns leaner and the AMG programming of the ECU wanted to burn richer, thus the rotten egg smell. So went to Chevron 94 with no ethanol and running fine now...no CEL or rotten egg smell and idles smooth.

BTW....Ethanol deteriorates engines parts even though it is okay to use up to 10% ethanol.

 

What kind of fuel did you put in your car and how many gallons did you fill up?

 

I consistently fill up with 93 octane (readily available at almost every pump where I live) and have had smooth sailing for 10,000 miles.

 

Ive ran 101 plenty of times on mine with no problems..

 

Ya I would think 101 octane wouldn't pose a problem...

 

Did I miss the memo...?