The fuse exists only on auto OB's and its specific purpose is to keep the AWD computer from being confused by the speed difference caused by a donut spare. The only speed limitation is the one imposed by the spare tire - 50 mph. You should *never* tow an auto AWD Subaru flat OR by one set of wheels - always use a rollback. 5-speeds can be towed flat in neutral. I've driven probably 100-150 miles or more with the fuse in because of a transmission problem I was having last year; no ill effects yet. And I did get wheelspin in the wet, but never on dry pavement.