premium or regular?
I drive a 1994 C180 Euro Benz usually on weekends only and it seems to be running better on the regular then the premium. Books recommend the premium, but the motor at idle with "D" on, feels like it is very tensed and vibrates a lot more then when on regular. We use unleaded here. I have changed to regular and it feels a lot more relaxed now and less vibrations although the car doesn't have the "go" it had on premium before. Is this the right thing to be doing or will I destroy the motor using regular only? Can I mix with half of regular and half of premium or should I fill with full premium followed by full regular and so on? Will the experts please comment on this???