With the cost of gas going out of site, can we use regular gas instead of premium? A mechanic I know says it will gunk up the engine, a guy who works for Chrysler told me that you can use regular as long as that's all you use and the computer will be happy, it's using different grades that screw it up; another guy told me he's never used anything but regular in his 2005 Coupe.

I have a 2005 roadster with 20k miles that's always had premium. Any money saving advice would be greatly appreciated.

Thanks