gogboy

Hello guys,im about to do another oil change on my X6 but i am totally confused on what oil to use once again! i have used castrol edge 5W 30 fully synthetic for years and then tried Mobile super plus 2000 10W 40 and didn't really notice a difference,but the hand book clearly states to use 5W 30 but so so so many people on here use 10W 40.

Is it a good idea to avoid listening to manufactures guide lines and use the 10W 40? even when i call mazda they recommend the 5W 30 but so many on here use 10W 40? i really don't know who is right,the people who designed the car or the people who have driven them for years?

I really cant make my mind up who is right.

any thoughts would be great.
Thank you all.