I thought the light would come on a little above the red line but it didnt come on till it was right on it. I went for about 8 miles before i called it quits and went in to the gas station. It was to nerve racking to see that stick almost to the bottom of the red line

 

With the SanGauge II in place, I see about 50 miles Distance to Empty when the light comes on. I once went as far as 14 miles DTE before filling up - cringing all the way - and ended up putting about 22 gallons in the tank. So it seems the owner's manual is reasonably correct in saying the light comes on when about 50 miles worth of fuel remains. But........... your mileage may vary so act accordingly.

BL Flank, '07 Adventure, blingfree