I just bought my son a 1990 300E w/144,000 miles.
Everywhere I look it warns to use only premium gas. Does anyone use low octane and if so have you experienced any problems?

 

i tend to use supreme fuel over at chevron with techron because of it's cleaner fuel, and for alonger lasting fuel filter.

 

I have only used premium in my 300E but some of my friends who have volvos and BMW's that require premium refuse to pay for it as gas in CT is among the highest price in the country and their cars idle slightly rougher but they still function.

 

By feeding your engine a higher octane gas, it will burn hotter in the engineand give you more power....one of my friends put regular in their M class mercedes once (going against my reccomendations) and it sputtered a little bit, but the car was driveable.
I personally put premium in.
Good Luck

 

It is designed and engineered to run on premium gas for optimum performance. I would suspect the computer would detect a lower octane fuel and adjust the mechanics of the engine accordingly. This would affect engine timing, idling and overall performance.