I'm ready to do an oil change in my 01 CLK 430 but don't know if it has synthetic or not. What should I do?

 

Synthetic by all means, that is the only oil aprroved for mercedes go here for all you'll ever need to know about MB oil requirements http://www.whnet.com/4x4/oil.html

 

Originally before about year 2000 Mercedes allowed natural oil in their flexible service plan cars.
Later there have been some litigation and they changed the recommendations to synthetic only.
Getting average 13,000 miles between oil changes, will get your money worth even with the most expensive oil.
BTW 2-cycle synthetic for my PWC cost well over $10/quart and it doesn't last at all.

 

Very informative link, thank you very much.