Read your hand book page 153, 154, 5-30 and 5-40 are OK.
Years ago i would have agreed to use a addative in the oil but not
now with with the new oils on the market. I live in Italy and drive a December 2006 X5 3.0d one of the last E53, before that 2 Range Rovers with BMW motors, a 530d and a RX300 Lexus and used Castrol 0-30 SLX in all, never had a problem at all, winter or summer. I also change my oil and filter every 5000 km.