While ridding in Ma & Pa Kettle country last summer I was forced to buy regular unleaded gas for my 1999 FXDS. Now I know there is no likely damage from running one or two tanks full of this stuff, but I thought it was kind of funny that I did not notice any difference in the way my motor ran. Running in hot desert country and climbing out of the Columbia River Gorge produced no strange noise or detonation. Same thing when crossing the Cascade Mountain Range into Puget Sound Country. What gives? My handbook says to run only premium unleaded, which I have except for this one time. Is the motor company not telling the truth about which gas to run and why?