Brian verbeek wrote about using untaxed diesel near equivelants.  Ok, 
first of all, the genuine diesel grade stuff marketed without the road 
tax in the US has very visible red dye, a little of which will 
contaminate a large amount of undyed fuel.  One local dump truck owner 
paid a fine for being caught at a road side inspection for using it, and 
I've seen few Westys that are advertised for less than the fine levied 
against him.  
  Typical excuses are that the vehicle was only used for "on site" use 
until this drive on the road, and it's  just mixed.  Also, some folks 
were adding ATF to the reformulated diesel fuel to give it more 
lubricity, which was a concern to many during the switch over.  Guess 
what color the ATF is dyed?  Sure caused some problems, and yes it's 
visible.
  Ok, going back in my reading a few decades, I well remember the test on 
the Mercedes 190 D in Mechanics Illustrated or symilar style.  Back in 
the great old days of Tom McCahill and such.  They specificially 
suggested using number two heating oil in the machine.  But that was a 
different era.
  I've heard the red dye is retained on parts so a quick switch DOES NOT 
remove historic evidence.
		John