> I've noticed something similar: if you have tool in the Bus, nothing
> you
> can fix with that tool will break.  But the day you accidentally
> leave
> all your 13 mm wrenches/sockets/nutdrivers at home, every 13 mm bolt
> on
> the car will work loose.

and here's why ... ;)

    Tales of the Workshop
    by Robert W. Service-Advisor   :)

            The Rules

  When they step up inside, as you go for a ride,
  And the first thing they see are the tools,
  Then they'll ask with a smirk if you do your own work,
  Cause they have no idea of The Rules.

  For it's Tried and it's True: What you carry with you
  Will help you get back; and it's certain
  What you leave back at home, as the country you roam,
  Will not help on the road when you're hurtin'.

  As you go through the years, you will learn from your tears
  All the tools you will need on the road,
  And you increase the weight, in attempts to cheat fate,
  Adding more and more tools to your load.

  Now, it's sad, but in trucks, fuel economy sucks,
  And gets worse with all that piled aboard,
  But the point we make here is that gas ain't so dear;
  Don't let tools and spare parts be ignored.

  So the bus weighs a lot. Even more when you've got
  All the spare parts your money can buy
  Hidden under the seat, stacked so careful and neat,
  In the hope Murphy's Law won't apply.

  But since Murphy still lives, and he seldom forgives,
  No matter how much you have pleaded,
  The Rules make it plain, but we'll state it again:
  Carry with you whatever is needed.