Regular or Premium fuel? [merged]

[Eclipse_98_RS]

Hi guys, my car is an all-stock RS, but I'm going to start doing some mods to it. Right now I just use regular unleaded gas, but when should I start going up in the octane? After intake/exhaust, or beyond that? I don't want to screw up my engine but I don't want to have to shell out more cash on fuel than I do now. I know, I'm a cheap bastage.

 

[PaintMunky468]

OK, I just got a 1998 eclipse gs-t. Now the previous owner took exceptionally good care it. He told me that I could burn either Premium, Mid, or Regular in it and that if I use premium I will have a noticable difference in performance.

Is this true, that it will perform better on Premium?

If so, which gas will prolong the life of the engine?

 

[LandoAWD]

Read your owner's manual.


Premium ONLY.

 

[97GS-TSpyder]

but there is always the exception


defiant....ask him what to use

 

[LandoAWD]

but there is always the exception


defiant....ask him what to use

No, there isn't.

He argues oil, not fuel. Why do you think race gas is high octane?

 

[pacent]

Although you could put in regular in your car, you will get better performance and gas mileage if you put in premium. Your engine will start knocking, and the ECU will retard the timing to compensate for the shitty gas. Just stick with premium, your car will be much happier.

 

[ikickuintheball]

What does it say near the gas gauge? . "Premium Unleaded Fuel Only"

 

[GSXpress]

On a side note.

Do you guys notice a difference in premiums from gas brand to gas brand? Or do you just get the cheapest premium you can find?

 

[ProjectTalon130]

On a side note.

Do you guys notice a difference in premiums from gas brand to gas brand? Or do you just get the cheapest premium you can find?

Most DSMers I know use Sonoco ONLY. They usually carry the highest octane but it depends where you live..I know if Ohio they have 95 or so octane as premium and here in CT is only 93 and you have to hunt for 94 or higher.

 

[doug]

I like Amoco Ultimate. I can't really tell a performance difference with other brands, though, but I feel more confident using Amoco. Sometimes I'll use Shell V-Power or whatever it is, if it's close to the same price (and Sunoco too, but we only get 93 here).

 

[FORMONTOYA]

in houston...exxon, shell, or chevron...all 93...no noticable difference between the 3...will not buy gas from 'cheap' station.


jim

 

[kyledykstra]

I can feel a definate performance difference in 87 vs 93 octane (I use 87 if I'm going to be road-tripping a decent distance).

and since I have a '90 gauge cluster, mine only says "unleaded fuel only"

 

[97GS-TSpyder]

No, there isn't.

He argues oil, not fuel. Why do you think race gas is high octane?

i remember DISTINCTLY him saying he took many a trips on regular and never had a problem...he didnt argue it he just stated it....i remember it...now im workin on finding the post....give a day or so

 

[blackGSX2g]

i remember DISTINCTLY him saying he took many a trips on regular and never had a problem...he didnt argue it he just stated it....i remember it...now im workin on finding the post....give a day or so

http://www.dsmtuners.com/forums/showthread.php?t=138642&highlight=regular+gas

There's Defiant's post on that..4th one down

I only use Premium, why give my car another excuse to detonate. It only ends up being a dollar or two more and I prefer to drive it hard.

If I didn't have a choice, I would turn down the boost and fill up with regular and not worry about it.

 

[Jeremoose]

There's a huge performance difference from premium to regular.. But if you want to save cash, just flip back and forth between premium and medium (or regular), always fill when your down to about half a tank, and you'll keep the octane levels at a decent level. Just my .02

 

[wret]

My ECU cuts boost and probably retards the timing when I use anything but premium (93 around here). I can tell immediately if a gas station rips me off by dispensing regular from the 93 pump and I don't buy there again.

If you're on a long road trip where you are not doing a lot of accelerating and you know you will burn through the whole tank, it may not be that bad. It takes quite a while into the new tank of high octane for the ECU to raise its restrictions though.

 

[marcmsj]

My ECU cuts boost and probably retards the timing when I use anything but premium (93 around here). I can tell immediately if a gas station rips me off by dispensing regular from the 93 pump and I don't buy there again.

If you're on a long road trip where you are not doing a lot of accelerating and you know you will burn through the whole tank, it may not be that bad. It takes quite a while into the new tank of high octane for the ECU to raise its restrictions though.

my clutch has been slipping for a while now, it's on it's last few miles now. i haven't been able to hit boost cuz of the slippage, so i figured i could get away with using regular for the time being and it's been fine. not something i would be doing though with heavy acceleration.

 

[mavisky]

I wouldn't use anything lower than 91 at any time, if you intend to drive it hard at all use the highest you can get. Around here i use mainly 94 octane sunoco, although during the winter i'll use 93 or even 92 since the car doesn't get driven much and the cool weather makes the smic a little more efficient.

 

[afieclipse5124]

Will Premium gas help my RS with gas mileage and power? Or will it not effect the engine since I have not upgraded anything yet?

 

[PaintMunky468]

Hey, thanks for the advise guys, im going to try and keep the premium in there. I was asken because the car didnt have an owners manual so I figured Id ask the owners.

And just to clear it up, I wont do any damage to the engine by using regular correct?

 

[marcmsj]

.. or you could just use some 87 octane and pour toluene in your tank

 

[doug]

Will Premium gas help my RS with gas mileage and power?

No, not really.

 

[Quasimondo]

Will Premium gas help my RS with gas mileage and power? Or will it not effect the engine since I have not upgraded anything yet?

If your RS is turbo, I don't know why you're not using premium. If your RS is non-turbo, then it won't help. Higher octane ratings indicate the fuel's resistance to knock and engine killing detonation, not more explosive fuel. Engines that have a high compression ratio or use forced induction require high octane fuels because that's the only fuel that will not cause knock. If your engine is naturally aspirated and has a low compression ratio (in relation to other high performance naturally aspirated engines) then there is no need to use premium gas when it runs knock free on regular.

As quoted from http://auto.howstuffworks.com/question90.htm

"The octane rating of gasoline tells you how much the fuel can be compressed before it spontaneously ignites. When gas ignites by compression rather than because of the spark from the spark plug, it causes knocking in the engine. Knocking can damage an engine, so it is not something you want to have happening. Lower-octane gas (like "regular" 87-octane gasoline) can handle the least amount of compression before igniting."

 

[baxsom]

not sure how it does in cars
but diamond shamrock here in texas causes the valves on my ZX9R to build up deposits that was causing them to not completely close

 

[mavisky]

Hey, thanks for the advise guys, im going to try and keep the premium in there. I was asken because the car didnt have an owners manual so I figured Id ask the owners.

And just to clear it up, I wont do any damage to the engine by using regular correct?

If you run 87 octane or so and you have raised the boost or even go wot your engine may begin knocking. If so you could be doing damage to the rings and could even risk damage to the rod bearings if the knock persists or is severe. Save yourself the aggrivation and just run 91 octane or higher.

 

[Defiant]

I was asken because the car didnt have an owners manual

Inexcusable.

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Any 2G Eclipse manual will be fine, too.