Regular is what is reccomended so use that. If your check engine light came on, check the gas cap to make sure it is tightened enough.1996 Federal regulations of OBD2 or On Board Diagnostics 2 made mandatory many new sensors in the engine, one of which will trip the Chek Engine light due to an unpressured gas tank... which can be caused by a loose fuel cap.There couldbe more reasons why the light is on, but that is the most simple/common one.