Tune-up

How Often Is A Tune-up Needed For A 98 Deville (north Stare). Had It For A Year And 5 Months Now. It's Still Running Perfect, But Maybe Thats Why I'm Not Getting Good Gas Mile......

i just had my spark plugs replaced and fuel filter at 90,000 miles. i have a 00 deville, i was told i'd need a tune up around 90,000 to 100,000 miles. but replacing your spark plugs would save u gas money. make sure u use the ac delco spark plugs not the cheap bosh ones.