Burr oaks can and do get oak wilt, but not to the same degree and severity as red oaks and live oaks.  Diagnosis from images is not 100% accurate, but in this case I am fairly certain that is not oak wilt.  The foliar symptoms are scattered throughout the crown, and the response of the leaves does not resemble oak wilt.  This looks like a general stress response to the brutal summer we have experienced.  The growing season is coming to the end, and the tree will be losing it's leaves soon anyway - this is just premature defoliation from the stress.  Do not change any of your normal maintenance practices, the tree should be fine and come out fully next spring.