I think this oil cap removal thing works from I can tell. However, I'm not sure I'm willing to live this way next winter.

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Current BMW's:
2013 E70 X5 xDrive35i Premium (mine)
2014 F25 X3 xDrive28i (hers)
Past BMW's:
2001 E46 325i
2001 E46 330ci
2003 E39 525i
2006 E53 X5 3.0i
2008 E70 X5 3.0i
2014 E84 X1