99 se-l...when accelerating normally there is a rattle in the motor...idling no rattle rev the car in park no rattle...my first thought was timing chain....but my wife put regular gas in it yesterday....only 1/4 of a tank...but I know we are supposed to only use premium in our cars...I'm thinking detonation in the cylinders...or maybe the plugs are toast...any help would be appreciated! Thanks

 

Replace simple cheap things first, see if that does it

 

We're only supposed to use premium? I use regular...

 

My fuel door says premium on the inside of it

 

premium is reccomended. personally on my auto i only used regular. I changed out the fuel filter and started putting in premium for like 6 tanks and noticed little to no difference at all. On my 5mt I only use premium though.

OP, i assume there are no codes since you didnt say otherwise. It could be many things unless you narrow it down. I say put premium back in for a few tanks and see if it goes away. Could just be cheap gas.