Sorry to share this. I do 5K oil and filter changes. NO burning or leaks. 180K on my 01'3.0 auto. What oil do I use? The 5/30W syn that follows all the certification and API guidelines. I buy 5 qt units from Walmart - Super Tech. Might go up to 5/40 if I can find it.
Locate the information on lubrication. It's all about certification. It's like the guy who buys a BMW when a MDX would have been just as good. It's more about driving style and how often you change it than the silly brand names.

__________________
X5 3.0 AUTO -2001 - 238,000 miles