On a 17 year old X I would absolutely start with new bolts. I would not buy official BMW bolts I will be getting black oxide 12.9 and washers. If they fit I will likely get the T nuts and epoxy them in place to convert my e53 to act like the new e70 that has threaded inserts in the axle support.

Once replacing the bolts I'll be simply set I'm opting for the forever 12.9 bolts.

If I got the 10.9 bolts I would torque to spec and keep track of the use count with a center punch and dents in the plate, replace after five uses or when torque drops below about 97 N·m before 90°

(That number might change higher or lower once I test with new bolts).

I linked above to a 15 pack of decent bolts for $17.

My determination is that the high force on the spec of the design is mostly for the well being of the CAR in a crash. The bolts can be at 1/3 of design spec and handle anything you can possibly subject them to by driving. That is why "everybody" gets away with treating the metal at if it's just for under belly protection and not an important part of the frame

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2011 E70 • N55 (me)
2012 E70 • N63 (wife)