My 99 SLK 230 has been sitting for the last 3 months, being driven only to the corner store and back once in a great while. Now that I am thinking of driving it again, I read in a magazine that gas can actual lose octane in a few weeks if left sitting. So, I am wondering if this is going to have an advese affect on my engine, since the Kompressors must have premium fuel. The tank is 3/4 full and I don't know if I should add something to the tank, drain it, or just drive it? One thing I DON'T want is for anything to turn on that blasted CEL. Any thoughts anybody? All opinions welcome.

 

there are octane boosters that you can buy,I used to have 69 mark 3 that had to have 102 octane and the booster worked very well. At that time it added about 7 bucks to a tank of gas. I sometimes let one or the other of my cars, slorslk, set all winter too and never had a problem. I never added anything. You might top her off though.

 

Top off with the best fuel you can get and go for a drive.
I doubt you will have any issues.

Bazzle