Just spoke to the shop foreman at the MB dealer and he said that there are no problems using vac system or topsider to evacuate oil as long as new filter is installed every time. so i will use the vac the next time it's due for oil change and see how that goes. I prefer not to go through the hassle of removing the bottom cover and drain the oil... I asked him about the oil change intervals and he said that changing it at 3-3.5k is a little overkill and he recommends 5k instead. his argument is that the 3000 mile rule was made over 30 years ago back when there was only one oil weight before the new oils and viscosity we have now. So in any case, adding fresh oil after 3K or 3.5K will not harm anything and i will still do it at these intervals since fresh oil means cleaner engines and with the vac system it shouldn't be that bad of a chore. By the way, he also said that MB is now using 40W-15 Mobil oil for older cars in place of 20W-50 .