Mikey: Yes, as of Feb 1 2001, MB insists that Mobil 1 be used for the free maintenance FSS services (maintenance is free during warranty period for 2000&2001). Actually I heard they may have OK'd some other synthetic oils for this, but Mobil 1 is preferred. The weight they want us to use is 0W-40. A couple of weeks ago we got this in bulk, no more sloshing quart bottles. I don't know if 0W-40 is available in quarts or not, we were using I believe either 5W-30 or 10W-30, it was a choice of 2 that we had that were lighter viscosity, or else there was a heavier viscosity available, I think it was 15W-50. But anyways we have the 0W-40 now, that is recommended year-round. Also to directly answer your question, yes, MB is paying for the Mobil 1. What you put in it after the warranty has expired will be up to you.......Gilly