Dear... I am a 300SL 107 1986 owner in Brazil, only 14.000 km and a few information here about... I would like to know how to adjust a mixture valve... In my car the plastic screw, on top, shows some Numbers and "N" and "S" position... A friend of mine told me "S" is for super/high octane fuel and "N" for ordinary (95 ron). I read some posts about enrich and lean (clockwise, etc) but I dont know how is the correct position and what happens when I change it... I have noticed when it is in "S" position there is a smell of fuel... Do I have to adjust with the engine running? Best Regards!