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When searching to buy front rotors, from any vendor, there is only one part # for rotors. Drilled rotors are directional for left and right side. Does Mercedes use one direction drilled rotors for both sides? Please correct me if I am wrong or misinformed.

 

1 direction.

Never paid attention tbh until you said it

 

Is that common for the C300 or do all MB models have the same 1 direction drilled rotors?

My C300 is the same way. I thought maybe it was an error of the previous installer of the rotors that they didn't verify the direction of the rotors before installation.

 

Actually many ventilated rotors are L or R, not just those that have cast-in ventilation holes (OEMs are rarely drilled since this weakens the metal and can lead to cracking around the holes). The correct orientation for a directional rotor is for the vanes to be tilted rearward as you view the hub, this promotes the desired flow of air through the vanes and out at the circumference of the rotor. The simple way of course is to just observe if you have different parts numbers for left and right sides ...

 

Many are however a Google image search shows otherwise for oems/replacements. Mine are replaced with zimmermans and my oems had same pattern, and looking through old threads it looks like people have the same.