MY DEAR HUSBAND JUST BOUGHT HIMSELF A G35, NOW l AM STUCK WITH HIS OLD 130T-SEDAN.l WAS TOLD TO ALWAYS USE 91-HIGH PERFORMANCE GAS.

THE CAR STILL LOOKS NEW AND RUNS REALLY GREAT, BUT IT IS A 1996.DO l LISTEN TO HIM AND STILL FILL THE TANK WITH 91 OR GO WITH A CHEAPER GAS(89) SINCE THE CAR IS GETTING PRETTY OLD?

If he is always used high performance, then l would not change it. But.. if you do not like the cost, and do not feel that the engine needs the best of the best, then do not keep using it. l mean l have a 2002 Jeep and l use the cheapest there is. I've used better, but honestly could not tell a difference.

if it has a big american engine go with 89 if not stick with 91 it will help the engine last longer :)

Always, always go with the octane level the manufacturer recommends for the car. If u put 87 octane in an engine that is designed to handle premium or super, you're going to have a lot of combustion problems & performance issues (backfiring & carbon build-up on the valves, to name a couple).

A car getting older is no excuse to put lower-than-recommended octane fuel in it. But if the manufacturer says the car can run on mid-grade, then run it-- l know how expensive it can get to fill a tank with premium after a while. Just check out ur owner is manual, & go from there! :)

For optimum performance u can use the 93 or 91 octane. Something l told my customers when l worked for Infiniti was that the engines were built with different timing than the Nissans. So its not a taboo to use lower octane fuel for ur Infiniti. To optimize performance & spend less use the 89 then buy for $1.50 STP octane booster. Many times the octane booster will bring the fuel rating higher than the 93 that we pay an arm & a leg for. On the fuel door of his G35 if it is 05' & older it should say premium fuel reccomended. 06' does not, instead phrasing it with ''Please use Premium Fuel''. On BMW, AUDI, Mercedes, & Lexus u must use premium or the car will not perform correctly. Nissan/Infiniti have made a wonderful product that allows u to utilize other fuel grades.
So to answer ur question go ahead & use a lower grade, but if u feel that the car has a lack of performance go back to the premium or use my suggestion & add octane booster before u fill up each time.