You probably know that the colder the weather the more likely you will hear a clatter when you first start an engine after a night of sitting because the oil takes longer to get adequate oil pressure to the engine. Since it is fine in the summer I would change the oil and filter and use a 5-40 wt. Mobil 1 or because of the extreme cold area you are in even 0-40. That will likely cure the problem without adding any other products.

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X5 4.6 2002 Black Sap, Black interior. 2013 X5M Melbourne Red, Bamboo interior
Dallas