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.
Short response: I don't Short response: I don't know. Long response: 5w-30? On an M5? vs. 10w-60? With the caveat that I have no idea what BMW recommends, I use synthetic 20w-50 racing oil in my E30 for track driving, and if I drive it in winter, would go to 10w-40 synthetic, or maybe 0w-40 or 5w-40, depending on how cold the weather temps would be that I'd be driving in. I can't imagine that 5w-30 would be recommended to be appropriate for a high-revving M5 engine driven in summer temps. I could see 5w-30 maybe for winter driving only (& someplace pretty cold through winter, at that), but given the operating range of synthetics these days, I'd think 5w-40 would be more like it. You might want to check any M5 specific forums, or special interest groups, see if there's any consensus. Search bimmerfest.com, bimmerforums.com, http://www.m5board.com/vbulletin/ or anything else you can google up. This post is dated, but perhaps still useful - whatever oil you use, you want to make sure it meets the required specs - which means you'll have to learn a bit what the oil specs are, what they mean, and research that whatever oil is used is appropo for your car. http://www.m5board.com/vbulletin/m5-e39-e60-tips-tricks/21574-oil-type-bmw-manuals.html Addendum to long response - since that post shows 5w-30 (meeting the correct specs) as a BMW-recommended oil, well, ok. I'm kinda skeptical that a 5w-30 offers the same kind of protection that a 10w-60 would, but I'm not an oil engineer. Something to check: if different oils are recommended through the engine's life for your M5's engine, such as if 10w-60 is recommended up to xx miles, and something different such as the 5w-30 for later down the road.