getting a car soon

wywern209

macrumors 65832
Original poster
Sep 7, 2008
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do you rly want to know?
Can you put regular gas in a car requiring premium? well, here's the story. i'm getting a job soon to pay for a car cuz im getting my license in jan at earliest. anyways, i did some hunting around and found a nice Mitsubishi eclipse GT for 3,995. all was well till i saw it needed premium and with the amount gas costs these days.. i found an eclipse GS. the GS takes regular at the cost of a 50 hp less engine but strangely enough, it costs more than the GT like 1k more for like 8,000 miles less on the mileage. soo anyways.. can u do it? btw, im looking for a nice looking car that doesn't cost above 4.5k MAX( lower is always better) and has some decent miles on it. like not too bad. here is a link the the eclipse GT i want.
 

iToaster

macrumors 68000
May 3, 2007
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In front of my MacBook Pro
No, you can't. If you put less than premium gas in it there is a severe risk that the fuel will ignite before the piston in the engine reaches the top of its stroke, thus you will experience something known as pinging and run the severe risk of breaking a piston rod... which will total your engine.
 

steve2112

macrumors 68040
Feb 20, 2009
3,023
6
East of Lyra, Northwest of Pegasus
Maybe not. The engine controller computers in most newer cars can recognize the the lower octane fuel and will retard the timing of the engine and adapt. The result will be lower horsepower and torque ratings, but no real damage. It really depends on how old the car is. If it were older than about 10 years, I might be wary. Anything in the past few years should be ok.
 

swiftaw

macrumors 603
Jan 31, 2005
6,309
20
Omaha, NE, USA

quagmire

macrumors 603
Apr 19, 2004
6,255
1,063
The cost between regular and premium is like $4-$5 each fill( in my experience). Just stop buying coffee at starbucks everyday and you'll be able to afford premium. ;)
 

iToaster

macrumors 68000
May 3, 2007
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In front of my MacBook Pro
That's only true for older cars. Newer cars have "knock sensors"

http://www.edmunds.com/advice/fueleconomy/articles/106293/article.html
I'm well aware about knock sensors, having dealt with a few troublesome ones myself, but they only tell the computer that the engine is misfiring, the need for higher octane is due to higher compression ratios so to prevent detonation before the desired ignition point due to compression alone.

Also, OP, knock sensors are found on almost all modern cars. A car made in 2000 will have one.
 

quagmire

macrumors 603
Apr 19, 2004
6,255
1,063
yeah but that can add up...
So does buying starbucks coffee...... :p

IMHO, it is easier to spend more over time then trying to save money by cheapening out on $5 which then causes the engine to blow up and then you have a $3,000 or more repair bill. ;) Easier on people to spread the cost of premium over time then being hit with a big bill in a short time period.......
 

wywern209

macrumors 65832
Original poster
Sep 7, 2008
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do you rly want to know?
any eclipse owner on MR? cuz i would like to know if it is recommended or required. because volvo recommends it but others require it. i don't know which of the 2 the eclipse is.
 

quagmire

macrumors 603
Apr 19, 2004
6,255
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do knock sensors detect the knocking after the knocks or does it reduce perf. to account for the lower octane?
Both. If the sensor detects knocking, it will retard timing to prevent damage to the engine. Which will reduce the performance of the engine.
 

electroshock

macrumors 6502a
Sep 7, 2009
647
0
do knock sensors detect the knocking after the knocks or does it reduce perf. to account for the lower octane?
It's sorta like the engine doing a ballet. Maximum power if the ballet dancers do their steps at right time. Wrong octane fuel throws the whole thing into chaos and a destroyed engine. Knock sensor accepts lower performance by telling the engine computer when it detects knocking/vibration so the engine computer can adjust fuel ignition timing to compensate for the wrong octane fuel.

Doing it like this preserves the engine at expense of lower performance and higher fuel burn. It's a tradeoff.
 

Rodimus Prime

macrumors G4
Oct 9, 2006
10,132
4
The cost between regular and premium is like $4-$5 each fill( in my experience). Just stop buying coffee at starbucks everyday and you'll be able to afford premium. ;)
you are a little off on your math.
An eclipes has a 13.9 Gallon give take. you average fill up in that car will be 11 gallons or so. At 30 cent more a gallon that works out to be less than $3 a tank.

I drive a car that take premuim and I do get SLIGHTLY better gas mileage. Back when gas was $4 a gallon I was about breaking even on the cost difference.
 

quagmire

macrumors 603
Apr 19, 2004
6,255
1,063
you are a little off on your math.
An eclipes has a 13.9 Gallon give take. you average fill up in that car will be 11 gallons or so. At 30 cent more a gallon that works out to be less than $3 a tank.

I drive a car that take premuim and I do get SLIGHTLY better gas mileage. Back when gas was $4 a gallon I was about breaking even on the cost difference.
That is why I said in my experience as my car has a 16 gallon tank.
 

yg17

macrumors G5
Aug 1, 2004
14,888
2,480
St. Louis, MO
Just get premium. My GTI requires it and I put it in. It will adjust with lower octane, but it's such a waste. You buy the car for performance, you should get all the performance you can out of it.

Also, using a regular on a car that requires premium, even if the car has knock sensors and will run fine on regular, you may see a drop in gas mileage, so it might cost you just as much to use regular due to the decrease in MPG.
 

Ttownbeast

macrumors 65816
May 10, 2009
1,135
0
This is why I prefer carburetors over fuel injection easy repair, easy tuning, less moving parts, less mechanical problems--and if you know what you're doing you can get 30 mpg out of a 1/2 ton pick up even with the lowest octane unleaded fuel.
 

RaceTripper

macrumors 68030
May 29, 2007
2,697
21
It's not just about timing retard to avoid ping. High compression engines require premium fuel to insure they run at peak efficiency and to benefit from the extra detergents in premium fuel. With modern ECUs when you run non-premium they adjust the timing, but it also reduces power and efficiency. You can actually cancel out being a cheap-ass about using proper fuel with reduced gas mileage as a result of timing changes. In addition, prolonged use of non-premium fuel might result in premature engine wear and need for expensive valve adjustments as a result of carbon build up in the heads.

If you want to be cheap-assed about using the correct fluids in your car fuel, then get a car that uses lower octane fuel. In the end the cost is likely higher to use the incorrect fuel.

My salesperson told me it's OK to use regular in my MINI. :rolleyes: I know better. The manual says to use premium & it's never had anything but that.
 

wvuwhat

macrumors 65816
Sep 26, 2007
1,157
35
I think you need to worry about buying a Mitsu with over 110,000 miles on it. That's asking for trouble. You need to think less of 3 dollars a fill-up and think more on the hundreds/thousands you'll be spending in repairs.
 

wywern209

macrumors 65832
Original poster
Sep 7, 2008
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do you rly want to know?
I think you need to worry about buying a Mitsu with over 110,000 miles on it. That's asking for trouble. You need to think less of 3 dollars a fill-up and think more on the hundreds/thousands you'll be spending in repairs.
meh, i've heard of many imports running for over 200k so im not too worried cuz i can't get a car for like 4k and expect it to have LOW mileage on it. all the toyotas n stuff are expensive and have way more miles than this.
EDIT: found this
 

Counterfit

macrumors G3
Aug 20, 2003
8,202
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sitting on your shoulder
This is why I prefer carburetors over fuel injection easy repair, easy tuning, less moving parts, less mechanical problems.
Wait, so rebuilding a carb is easier than replacing a borked injector? And changing the jets is easier than plugging a laptop into my car? Do you even know how many moving parts a fuel injector has?* And just how often do you have to rebuild or clean out your carb? Fuel injection now beats carburetors in everything: efficiency, power, reliability, cost, adaptability to changing conditions in, and demands on, the engine. You remind me of a guy who used to frequent a Subaru forum, who was absolutely convinced that: the Subaru EA series motors (3 main bearings, air-cooled, almost all of them carbureted), could produce more power, were more efficient, and were more reliable than the EJ series (5 main bearings, liquid-cooled, fuel-injected), engines. Guess what engine series is in the STI?
meh, i've heard of many imports running for over 200k
And how many of them were Mitsubishis? Not many I bet.
EDIT: found this
That would be a better choice than the Eclipse. :p


*: 2


EDIT: I just did some searching. The 2000 Eclipse GT has a 9.0:1 compression ratio, so you could probably get away with 89. My car's compression is over 10.0:1 and Subaru recommends regular. However, a few guys have logged then engine, and found that it runs better on premium.

P.S. In my searching, I found that the engine in the 2000-05 Eclipse was also in my father's 93 Caravan. :D It actually moved that thing along pretty well.
 

quagmire

macrumors 603
Apr 19, 2004
6,255
1,063
Why not look up an early 2000's Pontiac Grand Am? I have seen a few around within your budget and the 3.8 V6 takes regular and are bulletproof engines.
 

wywern209

macrumors 65832
Original poster
Sep 7, 2008
1,503
0
do you rly want to know?
Why not look up an early 2000's Pontiac Grand Am? I have seen a few around within your budget and the 3.8 V6 takes regular and are bulletproof engines.
o rly? i didn;t know that about the grand am. i found these 2
2000 grand am

2002 grand am

EDIT: i did some googling and some disturbing things came up. like the sideview mirrors falling off, car computers acting all wonky and the anti-freeze leaking out and other things. those are things that i don't want to deal with. i want something reliable that i won't have to worry about getting probs.