Any battery of the correct grouping will be fine. I've purchased my last few at Sam's and have been just fine.

They will come with venting accessories to vent the battery OUTSIDE the cabin. You will see the vent hooked up to your current battery upon removal. It's a small tube (like small vacuum tube, but grey if OE) that connects to the battery. There will be 2 vent holes on the battery, plug the other side with a plug that should come with the battery.

Edit: This is what I have had in the E53 X5 for the last 3 years. So far so good...

https://www.oreillyauto.com/detail/b...6/bmw/x5?pos=2

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2005 X5 4.4i Build 04/05 Maintenance/Build Log
Nav, Pano, Sport (Purchased 06/14 w/ 109,000 miles) (Sold 8/15 w/121,000 miles)

2006 X5 4.8is Build 11/05 Maintenance/Build Log
Nav, DSP, Pano, Running Boards, OEM Tow Hitch, Cold Weather Pckg (Purchased 08/15 w/ 90,500 miles)

2010 X5 35d Build 02/10
Nav, HiFi, 6 DVD, Sports Pckg, Cold Weather Pckg, HUD, CAS, Running Boards, Leather Dash, PDC, Pano (Purchased 03/17 w/ 136,120 miles)