suspension woes and engine weak
 

My Euro 1994 C180 is feeling like new shocks are due. I am feeling the harshness of the roads a lot more than last year. Is it the springs or is it the shocks? The car rides at a reasonable level except that 2 months ago I had to add a thicker pad to the RHD driver's side to reduce the sag. I reckon that Benzs should have soft suspensions which will cut out almost all of the road roughness like the Lexus. The rear shocks have no.1 printed on the sides while other C 180s of the same period have no. 6, I think. What is the difference? Maybe I have the wrong ones? Maybe the sports ones? Thats why they are harder? The engine also vibrates through the car and maybe the mounts are also due?

I was using Premium then changed to regular unleaded. Now I have gone back to premium and 98 octane instead of the 96 of other brands. The regular is only 92. Any problems? I don't feel any difference at all. Is there any way to tune up the engine by adjusting something?

I was using S when I drove on the highway. Is this appropriate or it should be the E? On S it felt a bit rough on the 100kmh roads. There is no 5th gear in this car at all. Maybe a 5th gear would be a lot more relaxed and smooth.