I changed over to Motul 5w-40 X-cess recently because I've had to top up on BMW genuine oil over the last 2 oil changes prior to the most recent 2. I've been running Motul for the 2 most recent oil changes and it's been running really well without needing any kind of topping up. Oil temps run at around 200-210F which is the range at which detergent is most effective in synthetic oils.
To be honest with you, if there was one CLEARLY superior [insert product here], you'd know about it because no one else would use the competition. I made this decision based on research and opinion of friends who I race my car(s) with. Just because I chose to trust their expertise and it works for my preference/driving habits doesn't mean its the right choice for all E90s
