Hi to all;

I have a 2002 Mercedes Benz C200 Kompressor Coupe (Evolution AMG Sport package), and it has a easy manual gear without clutch (sequential gear)
it run almost 110,000 Km and i had a small problem in the gear shiftting from 2nd gear to the 3rd gear
my Q's is: 1- when should i change the gear oil and filter ??
2- how can i check my gear efficiency ??

Regards

C200K