Premium Gas Recommendation, Gasoline Options

[DavidE]

I filled up with 93 octane premium last night. I'll see if I notice any difference.

The manual says to use 91, but my only choices are 87, 89 and 93.

Can I mix 1/2 a tank of 87 and 1/2 a tank of 93???

[JohnJohn]

I filled up with 93 octane premium last night.  I'll see if I notice any difference.

The manual says to use 91, but my only choices are 87, 89 and 93.

Can I mix 1/2 a tank of 87 and 1/2 a tank of 93???
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Not recommendable, because that could confuse the gas sensor and cause a problem. If you want to use lower than 90, use an octane booster, I recommend using premium fuel because the engine runs better and will have a longer life and efficiency.

[manybrews]

it wont "confuse" anything. There is no "fuel sensor" that detects the octane level.
the knock sensor detects knock, and nothing else. if it doesnt sense knock, you have nothing to worry about.
if you drive in extreemly cold weather, 87 octane may indeed be enough as detonation will decrease quite a bit with the increased air density.
but in normal driving, 91 (or better) octane is recommended.

[BradEndeavor]

I've done a lot of reading and research on this and found that here in California the possibility of carbon build up if you use lower octane (decent) fuel is remote, if at all. Now, using your brother-in-law's gas he had back in the barn for 10 years might cause a problem.

Modern engines will automatically compensate for lower octane to reduce the pre-mature explosions (aka: knock) in the piston chamber. But, the engine will not run as designed and will not perform to it's highest potential.

I don't understand why it is called premium and why it costs more. Additives? I guess. But, I got my Endeavor for the power/torque (well, for a few other things, too). The new Outlander almost has as much "power" (220 hp to 225 hp) as the Endeavor, but the Endeavor has 255 for torque to the new Outlander's 204.... using premium gasoline, of course.

Anyway, I'm following the manual's recommendation. My two cents and a half... this week. Next week it'll be three cents.

[peterac]

Yes, I have an Endeavor 2004 with 65,000 miles and I am running 93 oct with an octane booster (4+) = 97 octane. If I start out in the morning and drive I have no pinging. But when the temperature of the day goes up say 80 deg and I sit and idle for 10-15 min, after that the engine will not stop pinging no matter what.

Do you know about the TSB-05-13-002 PCM Reprogramming for spark knock/Engine pinging/MFI DTCs /Delayed A/T shift? Does it help?

Please contact me
rebrokrfl@aol.com

[utiheadbanger]

I was just curious, if you use 87 Octane, won't the ECU recognize this and retard the timing?
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It can only retard it so much.

[nack75]

why are you using 93 octane and an octane booster? thats completely unnecessary. of course its going to ping. i doubt the ECU can tune the timing in occordance with 97 octane. use 91 (10 gallons 89 + 10 gallons 93).

[Forever Endeavor...]

Please don't be misled in the slightest by all these people telling you that regular gas will screw up your fuel injectors, or mess with your OBC. It's horsecrap. I called Mitsubishi. They said that you CAN NOT DO ANY DAMAGE TO YOUR ENGINE using 87 or 89 octane gasoline. The only appreciable difference in not using high octane gas is a potential decrease in performance. I asked the tech to elaborate on what performance elements would be affected. He told me that you may experience slight decrease in acceleration responsiveness and nominal decreases in gas mileage. He also stated that this would be hardly noticeable, if noticed at all by the driver. The OBC is default set and tuned to 91 octane, but adjusts the fuel injection and ignition distribution for any octane at or above 87. Again, MITSUBISHI ASSURED ME THAT USING LOWER OCTANE GASOLINE WILL NEITHER VOID YOUR WARRANTY OR DAMAGE YOU VEHICLE IN ANY WAY.

[ishadow4478]

just read the entire forum and there are few stating that they get around 2miles per galon by running premium gas. the car is supposed to hold 21 gallons,
lets use 20gallons as nobody should be pulling in the gas station empty ;)

20gallons x 2miles extra per gallon = 40 extra miles to the tank.

40 miles = $7-$9 of cost depending on your driving and gas prices..

this is based on the people stating they get 2miles more per gallon....

[EndeavorSUV]

When I tried it after the 3 or 4th tank the engine had a lot of ping & knock

[Jonathan Falle]

Is that what that smells from lol? I just bought my endeavor 5 days ago so i'm just figuring these things out, i noticed that premium grade was recommended but i would think most cars would say that. I've been using 87 octane but might switch now...

[gotarts]

I got my Endeavor a week ago tomorrow. The dealer filled it with what I assume was regular. I've been doing a lot of city driving to get used to the feel of the vehicle, and was at half a tank around 125 miles. I filled it, from half, with 93 octane, and was at 150 miles at the half tank mark from almost all city driving. I'll let it drop to a little under a 1/4 tank and fill it again with 93 octane. I'm still getting used to the accelerator and tend to make a lot of quick starts, but it does seem to have a little more pickup now, as opposed to when I was test driving it, and when I took it home for the first time.

[jcosmejr]

Well I have been reading everyones post and decided that even though I am sure someone will refute I will share my personal experience. I have a 2wd 04 Endeavor, I too was confused about premium or regular. I began with premium and made my way down as price of gas has gone up. At 86k running on regular I have maintained in mixed city and highway 22mpg on regular. I don't have any pinging I barely feel the power difference. When my timing belt, sparkplugs, and water pump where changed the mechanic noted how well my truck has been maintained internally in the engine and body. I admit I am religous with my oil changes at 3k and once in awhile put that chevron injector cleaning in the tank. My driving habits have changed drastically, I would normally drive 80-95mph on the highway and now I top 70mph, I don't jack-rabbit, I shut the engine off when I am waiting in a drive thru or long light, when I see the light turn red I let go of the gas pedal, on the highway I try to get behind a closed trailer semi by two car lengths. I learned many of these techniques from the hypermilling forums but I am not hardcore as they are, and it's been a struggle keeping my foot light. While visiting San Antonio where I originally bought my suv a day after she bought her endeavor XLS and she told me she only runs regular and she has had no problems with her endy. I also have a friend who has an 04 Lexus GX with 54k and Lexus recommends premium and she has only used regular and she has had no ill effects. Even Mitsubishi Motors of America has said regular is acceptable with no ill effects to the engine both short-term or long-term.

[manybrews]

you will loose anywhere from 10 to 25 hp if you use regular unleaded.
you will probably also loose mileage.


you will not damage anything.


HOWEVER..... the car was designed for premium, and you should use what the engineers recommended. If you cant afford the extra 3-4 bucks per fillup, you probably shouldnt be driving in the first place.

[lewdwig]

I've run my Endeavor for four years on pretty much all 89 octane with no problems.

Certain brands of gas in the USA have a better detergent package (search top tier gas) that was developed in cooperation with some car manufacturers to address engine deposit issues.

[MD Endy]

Your manual recommends 91? I have an '06 AWD and mine recommends 87+, strange.

[KiT TeUnG 2549]

you will loose anywhere from 10 to 25 hp if you use regular unleaded.
you will probably also loose mileage.
you will not damage anything.
HOWEVER..... the car was designed for premium, and you should use what the engineers recommended.  If you cant afford the extra 3-4 bucks per fillup, you probably shouldnt be driving in the first place.
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I totaly agree with this comment. I mean yur not really saving bucket loads of monies between premium and regular. like he said 3-4 bucks cmon. Besides the reason its recommended for premium fuel is because of the octane rating. The reason is also because it needs the high octane to run at its most efficient because of the higher than standard compression ratio this engine is designed with. Running lower than specified octane rating will cause uneven burn and uneven and premature detonation , causing knock retard and sumtimes valve train clatter .

As the engines detonation sensors (knock sensor) picks this up it will constantlly modify the engines ignition timing and make it spray a bit more fuel than normal to try and even out the uneven burn and knock retard created by lower octane gas. So in hindsight , yull be burning that low octane gas at almost twice the rate than if yu had pumped the specified or higher rate of gas required. So attempting to save a measilly 3-4 bucks yu loose in performance , effeciency , and burn more fuel .

[juke box hero]

Interesting topic. I've used 87 octane for 3 1/2 years now with no problems. My Endeavor tows our pop-up camper better than my F-150 did. I get about 18 mpg in town (or pulling trailer on hwy) and about 23 on the hwy.

[anyadang]

I didn't know I was suposed to use high-grade in my 04 Diamante and Galant. I switched over for a few months when I found out and noticed no difference in performance or ecconomy.

I drive the Diamante everyday, and it now has 110,000+ on it - I've only changed the brakes.

-AYD

[WDRacing]

If you worked on cars daily you would know using lower octane can clog injectors and/or ruin fuel pumps. It can also cause rough idle, stumbling, hesitation, stalling, pinging, and not to mention turn your check engine on with misfire codes. I understand gas is expensive now but use a calculator to figure out how much you save by using low octane versus premium on a fill-up it's less than $5. And if that is still too much as least buy an octane booster to dump in the tank .
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Perhaps if you didn't use such broad strokes people would understand what you're trying to say.

Lower octane DOES NOT RUIN injectors. Some gasoline even high octane gasoline contains debri and such from ALL sorts of things ranging from transportation vehicles to storage tanks. The octane level itself does not ruin an injector...it's a valve that opens and closes it doesn't really care what flows through it. Lower octane fuel doesn't necessarily carry more debri then higher octane fuel. I've driven tons of cars on ALL types of fuel from alcohol to 87 Walmart Brand...never have I had an injector fail...ever. Fuel pumps burn up more from people running there vehicles low on fuel for long periods...not debri or various octane rating. Unless you're using alcohol and the pump corrodes...but I seriously doubt anyone has an alcohol injected Endeavor running around.

Lower octane is cheaper yes, but I have definitely experienced light knock under load. If you can avoid applying copious amounts of throttle you can get away with 87, but I personally won't run it anymore. Detonation or knock of any kind is ALWAYS a bad thing. Running lower octane, like already mentioned, forces the ecu to pull timing. Which in turn makes you lose power and mileage. Under a high load on a hot day the knock sensors alone are simply not enough to protect your motor from knocking and or damage.

*EDIT*

Everyone has their own personal opinions on this matter...obviously. The choice comes down to this, run 91 or better and get the full potential and no knock...or at least I haven't experienced any when using high octane, or run 87 and have the ecu pull timing. Bare in mind that when the ecu pulls timing the motor IS already suffering from detonation because the knock sensor picks it up and tells the ecu it needs to retard timing. So the guys that say run high octane or you get knock are 100% correct. Yes you CAN run 87, but YOU ARE getting knock.

WD