Doc, first of all, thanks for your reply. What specific weight oil would you reccomend for the 99 E320 which, by the way CI is, a GAS engine. Even with my limited MB knowledge I know that much. And keep in mind we are in south Georgia where it gets hot in the summer and usually only cool in the winter except for a few days. However, we recently had a 2 week stretch of lows in the mid teens to mid 20's. Thankfully it has warmed up but today we had about a month or twos worth of rain. Again, thanks for the help!!