Is it really necessary to use premium gas in a 2004 Eclipse GTS?

I think its only recommended that you use premium, not required.

you will get better gas milage and your car will run smoother if you use it

If the GTS's V6 is designed for premium (which if i remember correctly, it is), you should stick with that. Basically there's a certain quality level in premium fuel, and if you drop down, you'll start wearing the fuel system out. also, the engine's made to run on premium so you wont get as good of gas mileage and power. Stepping up in octane is always good, but avoid stepping down if possible.

They recomend running premium because of high compression. It keeps the motor from predetonation or "knocking" or "Pinging". Too much knocking will end up wearing the motor out. As far as gas miliage.. I have never noticed or heard of a significant difference between regular or premium. So its good to go higher octane. 10 gallons at $3.30 for regular = $33 10 gallons at $3.50 for premium = $35 $2 every fill up isnt bad for a relyable motor.

Generally speaking the octane ratings are higher than advertised. That is a 'minimum' rating after all. However, that being said the comments on pre-detonation wearing out the engine or damaging the valve train are true. Another trouble may be incomplete combustion, which can cause run-on after you turn off the engine (less common but not unheard of in FI engine). Also wears out the engine because the revs drop way down and cylinders fire unbalanced causeing uneven strain on the rotating assembly. My opinion would be not to drop below 89 octane in your car requests 91. Granted I would recommend the 91 just because they generally have more ditergants in them and keep your valves from sticking in the long run.

i have an 03 eclipse GT and i put plus in my car. it runs great! but prices suck. lol

remember one thing.. when you use a lower than recommended octane fuel in a high compression engine, several things happen. 1 the timing will retard because the knock sensor senses engine ping. Thus.. 2 , lower power, 3, rough idle, 4, mpg will decrease. Use lower octane long enough and you risk burning holes in the pistons and making a mess of the valves

I am so upset. I have a Mitshibushi 2003 Eclipse GTS V6. My husband said you don't necessarily need premium but can use unleaded. Now the darn thing is running rough. I have a check engine light on and took it into a mechanic and he said I have a vacuum leak and its runs rough and sounds terrible when starting up but not in a minute, it stops and runs smooth. Mechanic said it would cost around $1,600 to fix. I love this car! Ugh, I am never going to listen to him again, When I had premium in there I had no problems....................

We have Mitsubishi Endeavor 2005, since 2006. It requires premium gasoline which I must use it or damage to engine could be severe. Next time before buying another vehicle I will be looking in owner manuals first. It hurts a lot at gas pumps. I wouldn't buy next vehicle which required premium gasoline, no matter what. I tried using lower grade but it ended using more gas.

Its good to have high octane only if your car needs it,most cars are now engineered to run on basic fuels.The issue is that using cheaper fuels will contain moisture and less detergents that help clean the engine.Higher octane fuel contains more detergents and increases the ignition timing which might reduce knocking on certain cars.It might also slightly give you better mileage but it will not give you better mileage that what your car originally gave you when it was new. It will MAINTAIN that mileage.As long as you don't go lower than what the manufacturer recommended in octane levels you will be fine.Good luck

I have an 02 gt that recommends premium fuel and I have used both and the only difference that I have noticed is that the high end performance is slightly reduced running 87 octane .

higher octane = longer explosion burn time which pushes on the piston longer and increases power and mileage. Shorter explosion time damages parts over time. I can get 35+ mpg on the highway easily with premium.

I just recently purchased a 2003 Mitsubishi Eclipse Spyder GS and I love this car. I practically stole it and $550 for it and it needed a timing belt and naturally the water pump and tensioners the whole kit and my mechanic did all the work including parts that I bought for $550 so I have $1,100 into the car. I took the advice of the manufacturer and topped off the tank with premium and it just drove like a dream. I also firmly believe and using Lucas gas treatment 4 oz / 16 gallons of fuel. Money was a tight one month and I dropped down to regular unleaded I didn't notice decrease gas mileage but I did notice at low idle was a little more of a stutter so I started using premium again and problem completely went away so I would highly recommend using premium gasoline. Tom from Tampa

Regarding Gas grading. Got my 2004 gts convertible 2 months ago. Love it but took me a while to get it to pass inspection. Car started doing the whole shebang with the hesitation, cutting power, unable to accelerate... then I remembered a video about fuel pressure and Premium Gas, read this thread, went to the gas station and filled up the second half with the tank with premium, the whole thing slowly went away with me driving around for 20 mins. AWESOME!

Regarding the first answer "I think its only recommended that you use premium, not required." I believe the fact that Mit. makes this a recommendation instead of requirement seems like a strategy to sell the car to me. USE PREMIUM! ;)

I have a 2001 Mitsubishi Eclipse GT Spyder 5-Speed Manual Convertible and it states PREMIUM GAS ONLY on the Inside of the gas cap. So I ONLY use PREMIUM GAS... IT SPEAKS FOR ITSELF...., SO PLEASE USE PREMIUM GAS ONLY AND SAVE GOOD MONEY. I paid $1200 for Her April 2016 and I've been BLESSED to still drive Her today 2019. I talk to Her and let Her know that She's a BLESSING TO ME and IF I TAKE CARE OF HER SHE WILL TAKE CARE OF ME IN RETURN..I Always heat her up Good before driving Her in the Winter. Every Oil Change I fill her up with PREMIUM GAS and a bottle of Gas Cleaner Together to get out old dirt and trash maybe built up. She's Quiet when I start Her up!! I LOVE MY CAR and I'm GRATEFUL, BLESSED AND THANKFUL for Her, #AmenOnRepeat-MsDee

EVERY OIL CHANGE I FILL HER UP WITH PREMIUM GAS 93 AND GAS TREATMENT.... SHE STILL RUNS GREAT 2 YEARS LATER!!!