I will agree with what Ricky is saying, if you notice it, do the boots immediantly,

I let mine go to long which is why i am just going to replace the axle, i did a total of 6 boots on 3 different cars last year before i bought my X and redoing another axle once again now on the X wasnt on my bucket list. Im just going to replace it cause i dont want the mess plus ive driven on it for so long im sure its contaminated, maybe not, i'll keep it anyways in case lol.

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2006 X5 4.8is Fully Loaded