I have a 1995 Mercedes E320. When I bought the car it had been previously running on unleaded. I stopped using uleaded because I noticed that the gaudge would read almost full while the tank over flowed, but when I use supreme it fills all the way up and the gaudge reads full. What damage can this cause to my car? What may be the cause of this? What should I do? Any help is better than none thanks.

First of all, no damage is possible. Secondly, the problem may be with the float in the gas tank. Thirdly, the problem you describe has no relationship between different octanes.

I have never heard of such a problem but if everything you say is exactly true, than I still feel the problem is inside your gas tank.

I do indeed wish you the best of luck with this one. It's tough!