I would normally agree with you about staying to the right unless you need to
pass or something as that is what I normally do.  But we were talking
specifically about I-40 from Tennessee to California.  There is a steady
stream of big Mack trucks in the right lane and alot of times they will want
to go faster than you.  They have to stay to the right (I saw alot of signs
that said that it was the law).  So unless you want a big rig passing you
every 30 seconds or want one tailgateing you while you follow another one a
little too close, I recommend staying to the left.  Just one of those special
exceptions to every rule.
Spares:
A couple gallons of water/coolant
A couple quarts of oil
A bottle of Moroso ceramic block sealer for long trips
Let the good times roll!
Ken Wilford
Van-Again
John 3:16