I recently took a chance on a high mileage 07-reg Mercedes-Benz E-Class 280 CDI (103k miles at three years), based on your hypothesis that oil degrades less with very high mileage driving. The car has had full M-BSH, with six oil changes to this point. I'm now set for 8k to 10k miles per year and have always changed oil at 5k miles as per your frequent advice. ALL my local Mercedes-Benz dealers say interim changes are not necesary but I am unconvinced and intend to have them anyway, conducted by a trusted local unfranchised garage (I intend have the "regular" servicing done at a Merc dealer, to maintain the 30 year corrosion warranty and breakdown cover). So, given the 16k my ASSYST indicator is giving, should I change the oil approximately every 5k miles or split the difference at 8K miles? Anything else I should watch out for?