Motor oil question...

[nikita]

Hi everybody,
So my question is how often should i change motor oil in a twin turbo charged engine(bmw x6 4.4, driven pretty hard)
Owners manual says 25.000km(15.000ml)
Official service says that it's better to change it every 10.000km(6.000ml)
I'll be very thankful if u'll give me a couple of useful links about this question
Thx

[dabigbratj]

seems like alot in all of my cars and in my older single turbo car have always changed every 3kmiles