I change oil on my '96 E320 . A very easy job. I've been using Mobil1 for 3 yrs now, MB recommends 0-40W but I've used both 5-30W and 10-30W (have not used 0-40W yet), so far no problem. I go 8-10K miles before changing oil and filter. I used to change oil at 3-4K miles, that's why I switch to Mobil1 , just so that I do not change oil often. You could find Mobil 1 on sale at Pep-Boys for about $4.50/ qt... If you don't mind changing oil, stay w/regular oil , about $1-$1.25 / qt and change every 3-4K miles... same end result