i was thinking about changing from premium to regular. I bought my car used about a month ago and the owner told me that the car is too used to premium. the car has 150,000+ miles on it so i was wondering if this is a good idea.

you drive an SE, regular is fine in your car

Exactly, unless you have a high compression engine or power adders such as an SC or Turbo...you can use lower octane fuel.