[Fat Charlie]

Even a small mpg gain counts for a lot against "this spot might rust earlier than otherwise." Keeping drilling to a minimum is obviously the best thing to do and protecting any holes you make only makes sense, but a car burns a lot of gas over its lifetime. The fuel log here keeps track of how much money you're actually saving over EPA, and a little bit of savings adds up a lot.

I'd protect any holes I drilled, but any measurable fuel savings would add up long before potential rust made me drill new mounting points, much less caused real problems.