Good idea, I guess I was just wanting to do what I thought was best by getting the synthetic, more expensive stuff.....guess I was wrong. I actually just found an 8 page list from the manufacturer that came with the car that has all the oils and fluids that MB approves of for the car and sure enough Castrol GTX is on the first page! Thanks 79, I will give it a go once I recoup some more funds....just spent close to $200 for a HID kit which I should be getting shortly.