Which ever oil you choose, it’s important that it meets the standard stipulated by BMW for your particular model.

For X5 diesels with the M57TU (aka M57N) engine (2004-2007 models) the oil should meet BMW LL04 standard.

I’m not 100% certain if the early X5’s fitted with the older M57 engine have a DPF fitted, if not these can use BMW LL01 or BMW LL04 oils.

I think it worthy to note here that Castrol Edge 0W-40, at least the version that is available in Australia, does NOT meet BMW LL04 standard

Castrol Edge Sport 0W-40 does meet BMW LL04 and is what Castrol recommends for the X5 fitted the M57TU/M57N engine and DPF.
They also say that X5 models without a DPF can use Castrol Edge 5W-30, 5W-40 and 0W-40 (BMW LL01).

I believe Castrol SLX Professional Powerflow 5W-30 is what many dealers use, and meets LL04 standard although some people say this is not available in small containers.

Other Castrol oils that are BMW LL04 certified are Castrol Edge Professional Longlife III 5W-30 and Castrol Edge Professional OE-X 5W-30 although there could be others.

To see the technical data on all Castrol oils select “Technical Data Sheet” from the main Australian page, then select “Search by Category” for Engine Oils. From there you can view a PDF document for every oil in the range. Within this document it will state what standards it conforms to, amongst a lot of other technical data.