Hi There...Does the GTZ need premium fuel ?

Teh GTZ does not require Premium fuel, but it can't hurt (except in the wallet).

I would recommend using premium even though it's 20c more than regular. The engine is built to use premium gas and if you don't use it, mileage and power do suffer. The engine detects the lower octane level and adjusts, but not in a good way... It's a pain and expensive, but in the end the car will like you better for feeding it premium. Not to mention damage to internal parts like heads and injectors from prolonged use of incorrect fuel octane. Improper combustion, burnt rings, valves etc..

Need, no. Mitsubishi recommended, yes. Good idea to run with premium, in my opinion, yes. Here's why, or at least some personal experience as to why you'd benefit by running premium: I bought my 1999 Galant GTZ in Dec '08. For seven years I ran premium, as recommended. When gas prices started to clime, I opted to use mid-grade, with occasional premium tanks every third or fourth tank. Regular oil changes and regular maintenance followed pretty well. As of yesterday, I rolled 235,000 miles. Testament to running premium the first seven years? Most likely. I've not had any major engine work needed, but a small oil leak around the head gaskets has been present for a couple years. Usually only a quart low at every three to five thousand mile oil changes. I'll stick to adding a quart when needed, versus changing out the head gaskets. Performance-wise, you'll notice a bit better if you stab the accelerator running on premium compared to mid-grade. I'm sure in my case, it's prolonged the life of my car running the premium as long as I did. On occasion, I'll throw a tank of premium in, if gas prices dip dramatically. Otherwise, I'll keep running on mid-grade. That's my choice, given the number of miles I've driven. If you care about your car, and can afford it these days, run the premium. Or, switch off every other tank to keep fuel system and related engine parts running as intended by Mitsubishi. Certainly, the number of miles on the car and how long you want the car to run well will tell you whether to run premium normally, or if you can "get by" with mid- grade. Personally, I feel it would be foolish to run 87 octane. Buy a car that normally runs on regular gas, if cost of premium or mid-grade isn't in your budget. Hope this helps, even if a year old in response.

look at cluster where gas guadge is,if it is premium fuel onley,it will say it,or unleaded fuel onley,which means u can run 87 oct or 89 oct.

Not on the '99 Galant GTZ. There's a sticker on inside flap of gas fill cover stating premium fuel only.

Today's date is 2-11-17 and I have had my Galant GTZ brand new since 8-1999. I have owned this great vehicle for apx. 18 years and it still looks great and runs great. The car runs much better on premium gas in every way performance wise. You will actually spend more money on gas using regular and mid grade because the engine burns lower octane grades way faster to try and compensate. At the end of the rainbow use premium because you will actually save money in gas and the car will perform as designed and put a smile on your face.