As many of you know that E39 M5 that were made prior to 03/2000 were using 10W-60 TSW Oil. Cars that were made after 03/2000 started to use 5W-30. Here my question. My M5 was manufactured in 03/2000. I purchased it in 2007 with 70K miles. At 75K miles did oil change at SCHOMP BMW Dealership. They used 10W-60 TSW Oil. Next oil change was done at 90K miles and it was at Murray Motor Denver BMW dealership, they also used 10W-60 TSW Oil. Now this is where it gets interesting; at 102K miles I took my M5 to back to SCHOMP and they used 5W-30. They are claiming that this oil should have been used since day, even-though at 75K miles they used 10W-60 TSW Oil. Could anyone please tell me what should I use; 10W-60 TSW or 5W-30.