I remember back , away back when I was in aircraft school when we were working on airplane engines ( Mostly Hemi's) we were given a basic class on fuels. I do remember we were working on a B-25 bomber that was converted to a executive plane for Union Big Shots. It used 110 octane fuel. We were taught that the reason they put tetra ethyl lead in the gas was to slow down the burning rate and make in smooth and constant. Regular fuel with low lead exploded in very uneven explosions Regular was actually more powerful than the higher octane fuels. Detonation caused the piston to get kicked all over the place. During WW11 , some of the Fighters and Bombers used water injection for short bursts of power. It did almost the same thing as lead except it carried its own oxygen which gave more power and also cooled the cylinders at the same time. It was very hard on the pistons and cyl. heads. Now to mileage. I worked at a foreign car dealer for several years in the early 70's. I had a customer who had kept fuel mileage of his car on every tank for 72,000 miles. He would use regular for awhile then switch back to leaded. He always got 1.5 to 1.6 more MPG with leaded than when he used regular. I found that very interesting. Just some thought food. Gary Barker ------------------------ Yahoo! Groups Sponsor --------------------~--> Yahoo! Autos. Everything you need to know about buying or selling a car. FREE Quotes, 360° Tours, Research, Blue Book, Compare Vehicles, Buy Used http://us.click.yahoo.com/kEZsdA/bwnGAA/YiGOAA/8LmulB/TM --------------------------------------------------------------------~-> To send a message to this group, send an email to: Chrysler300@xxxxxxxxxxxxxxx For list server instructions, go to http://www.chrysler300club.com/yahoolist/inst.htm Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/Chrysler300/ <*> To unsubscribe from this group, send an email to: Chrysler300-unsubscribe@xxxxxxxxxxxxxxx <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/