Join Date: Jan 2006
Location: Lawrence, KS - Rock Chalk
Car Year: 2010
Car Model: Legacy 3.6R Limited
The only reason you should put the fuse in (and automatics only have this feature) is when you have a flat and need to use a different sized temp spare. It saves the diffs from damage. It's strictly for temporary usage. There is no benefit MPG wise from all the reading I've seen.
2010 Leg 3.6 R, 2013 OB, 2001 OB, 2001 Forester S and 1999 Miata