For any of you interested in a very detailed technical paper written by three Mercedes engineers,titled "Extended Oil Drain Intervals - Conservation of Resources or Reduction of Engine Life (Part 2)" May want to order this 23 page paper Number 981443 from SAE (Society of Automotive Engineers) at
http://www.sae.org/BOOKSTORE The cost to download is $10.00 After reading this paper you may not feel guilty about extending your oil change intervals considerably.