I have the same car and have found for the best gas mileage and performance ( even though gas prices are through the roof ) premium fuel (91 or better) is the best by far. Any time i have used anything less the power is not there for me when i step on it(I tend to drive with a heavy foot). Here is a great handbook for some D.I.Y. common problem fixes as well as some good mods for your vehicle. http://www.lisst.com/ss_handbook.pdf Hope I was able to help!!!
Try 87 octane as long as it does not "ping" excessively you should be OK
regular unleaded - 87 octane
Gas engine 10w30 Diesel engine 15w40
195 degree.
The 2004 Chevrolet Impala runs on regular unleaded.
The 2005 Chevrolet Impala runs on regular unleaded.
The 2001 Chevrolet Impala runs on regular unleaded.
The 2014 Chevrolet Impala runs on regular unleaded.
The 2003 Chevrolet Impala runs on regular unleaded.
The 2002 Chevrolet Impala runs on regular unleaded.
5w30
R134a