Hi all, really need your help here. My x's battery has been used for 4 years and the BMW Service in HK suggest that I should have it replaced. However, I feel fine with the old battery since it works really very well, no problem at all. So do I really need to replace the battery right now? If yes, is it can be done by myself? Could you please provide some instruction for replacing the battery. My X is 2001 MY 4.4i sports pachage. Thanks!

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--2004 E53 X5 4.8is - ECE version; right hand drive; Located in Hong Kong; ext. black sapphire metallic; int. leather black; adaptive dynamic bi-xenon headlights; 16:9 onboard monitor w/o navigation; 20" genuine BMW Y-spoke 214 wheels with Bridgestone Dueler H/P Sport tires; Int. rear view mirror w/ compass.