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-   -   Fuel grades? (http://www.wranglerforum.com/f274/fuel-grades-154563.html)

Justindm 04-19-2012 06:58 AM

Fuel grades?
 
Anyone notice major differences in the fuel grades or is it just as good using 87 oct with additive?

daggo66 04-19-2012 07:00 AM

The only difference using anything other than 87 is that you will spend more money.

The Ugly Jeep 04-19-2012 07:14 AM

I have run 89 octane for all but two fill ups. Those two were 87. Engine was noticeably louder with 87. To me the extra $1.25 a tank is worth it. MPG is a hair better but probably less than 1 mpg gain.

The Ugly Jeep 04-19-2012 07:14 AM

[QUOTE="The Ugly Jeep"]I have run 89 octane for all but two fill ups. Those two were 87. Engine was noticeably louder with 87. To me the extra $1.25 a tank is worth it. MPG is a hair better but probably less than 1 mpg gain. I have just over 12000 miles and it's a3.8

kjeeper10 04-19-2012 07:20 AM

93 here.....,.... Superchips :eek:

ThingsAbove 04-19-2012 07:40 AM

There is zero advantage to running a higher octane than recommended by the manufacturer in any modern fuel-injected engine. If the engine is designed and programmed for 87 then 89 or 92/93 will have no effect other than to cause you to spend more money.

Any positive effects you notice are placebo effect.

However, if you've modified your engine programming (through chipping or a programmer) to advance timing then you should use the octane rating recommended by the chip or programmer.

Now there are differences in the fuel additives from different distributors though the additives are the same for all grades from a given manufacturer. So there may be an advantage in buy a brand name fuel (Shell/Marathon/Exxon) over what you get from your local Super Sloppy Mart.

FYI: http://www.ftc.gov/bcp/edu/pubs/cons...tos/aut12.shtm

http://images.thetruthaboutcars.com/...es-282x350.jpg

Megafriday 04-19-2012 08:14 AM

Octane rating is the measure of a fuel's resistance to pre-detonation. Higher compression engines need higher octane (more resistance to pre-detonation) to avoid the spontaneous, early detonation of the fuel mixture on the compression stroke, which is noticeable as engine knock or pinging. Higher octane fuel does not have more explosive energy than lower octane so unless you've upped your compression ratio or advanced your ignition timing, which is what the Superchips do for you, there is no advantage to running higher octane.

On high compression engines, the higher octane fuels don't make the power. They just keep you from blowing head gaskets due to uncontrolled explosions of the fuel.

JeeperYJ 04-19-2012 08:29 AM

love the sign
 
:dance:Love the fuel sign:punk:
Quote:

Originally Posted by ThingsAbove (Post 2277654)
There is zero advantage to running a higher octane than recommended by the manufacturer in any modern fuel-injected engine. If the engine is designed and programmed for 87 then 89 or 92/93 will have no effect other than to cause you to spend more money.

Any positive effects you notice are placebo effect.

However, if you've modified your engine programming (through chipping or a programmer) to advance timing then you should use the octane rating recommended by the chip or programmer.

Now there are differences in the fuel additives from different distributors though the additives are the same for all grades from a given manufacturer. So there may be an advantage in buy a brand name fuel (Shell/Marathon/Exxon) over what you get from your local Super Sloppy Mart.

FYI: The Low-Down on High Octane Gasoline

http://images.thetruthaboutcars.com/...es-282x350.jpg


Peepers 04-19-2012 09:08 AM

theoretically if your higher octane fuel was less ethanol, then you would see better mpg. $0.20/gal better? who knows...

ThingsAbove 04-19-2012 09:44 AM

Quote:

Originally Posted by Peepers (Post 2277990)
theoretically if your higher octane fuel was less ethanol, then you would see better mpg. $0.20/gal better? who knows...

Ethanol is actually used to raise the octane rating for gasoline. Pure ethanol has an octane rating of 113. But as you noted has less energy than gasoline. So it's possible to get worse mileage with higher octane fuel if the distributer is using ethanol as the sole octane booster.

On the other hand, ethanol absorbs water and as it does (in high humidity) it actually lowers the octane rating of the fuel it is mixed with so your higher octane pump gas may lose as much as 4% of it's octane rating as it ages in your tank.

But given that the EPA has banned all the good octane boosting chemicals and the guberment subsidizes the ethanol industry we have the byproduct of our elected officials.

All for our own good since they know best. :whistling:

snikt 04-19-2012 09:52 AM

Been using regular (85) with no issues

kik 04-19-2012 10:02 AM

Quote:

Originally Posted by snikt (Post 2278141)
Been using regular (85) with no issues

Altitude. 87 for the rest of us at sea level.

TrueNorth 04-19-2012 11:41 AM

I use 87 and "economy" modefor DD, the Unichip I have installed is tuned for 91 octane on "sport" mode so I'll fill up with 91 for wheeling trips and let her rip.

Mr. Sinister 04-19-2012 12:01 PM

My 2010 pings under load on 87 and 89, so I run 93. No ping.
Average mileage is 18mpg back and forth to work, 24-25 pure highway driving, calculated by hand.
Bone stock auto drivetrain, wheels, and tires. Just a spacer lift.

Just the facts.

kjeeper10 04-19-2012 12:59 PM

Quote:

Originally Posted by Mr. Sinister
My 2010 pings under load on 87 and 89, so I run 93. No ping.
Average mileage is 18mpg back and forth to work, 24-25 pure highway driving, calculated by hand.
Bone stock auto drivetrain, wheels, and tires. Just a spacer lift.

Just the facts.

We discussed this before. After installing the 35's and setting my tune to stock, the jeep would ping pretty good accelerating. Especially @ lower Rpms.
Doesn't do it tuned if I'm easy on the gas.
Also if I don't use Shell gas. If I'm near empty and fill up somewhere else I hear some light knock/ping under load.
With Shell gas she's quiet..... Strange :)

firehawk 04-19-2012 01:09 PM

Fuel
 
:dance:HI, use 87 reg. in my 2012, also used the same in my 07..:thumb:

CiDZillA 04-19-2012 02:24 PM

I've got a shop that sells Regular and super (87 and 89) for the same price. I end up using the 89 but I've never seen or felt any difference when using other grades.

rics1997 04-19-2012 02:31 PM

Running 89 octane wouldn't be too bad. There probably is a slight difference but doubt the cost will out way it but I guess it could very slightly. Other then that, without a tuner higher octanes are not tuned for your Jeep. Tuners like Superchips can tune the engine for higher octane but without a tuner it just isn't worth it.

adg44 04-19-2012 03:29 PM

Rather than trying to use mid-grade (89) or premium (91/93), you should be focused on using a top-tier gasoline like Shell and putting in the recommended regular 87 octane. Top Tier Gasoline

- Anthony

OH9JK 04-19-2012 06:41 PM

Quote:

Originally Posted by kjeeper10 (Post 2278881)
We discussed this before. After installing the 35's and setting my tune to stock, the jeep would ping pretty good accelerating. Especially @ lower Rpms.
Doesn't do it tuned if I'm easy on the gas.
Also if I don't use Shell gas. If I'm near empty and fill up somewhere else I hear some light knock/ping under load.
With Shell gas she's quiet..... Strange :)

My Jeep likes Shell gas too

Mr. Sinister 04-20-2012 06:20 PM

It's funny, I use Shell exclusively. Still pings on 87 and 89.

Casotakar1229 04-20-2012 06:23 PM

87 is same.

XJ Knight 04-20-2012 06:26 PM

All you guys talking about shell.. I haven't seen a shell gas station in 4 years

As to gas for your Jeep.. If your using anything other then 87 your wasting your money but the gas companies thank you

Disraeli 04-20-2012 06:31 PM

I'm still on my first tank but that tank is 92 octane non-ethanol.

So far, the computer is telling me that I'm averaging 14.2 mpg.

Do I care? Not really, but I'm going to do it for a couple more tanks as an experiment.

Then I'll probably switch to 87 and never look back.

Jurhip 04-20-2012 07:30 PM

I believe the 3.8l has knock control. No modern engine with it should ping regardless of load. If it is, it is a sign something else it not right (tune, plugs, knock s sensor, O2 sensor...)

OP, higher octane does not mean "better". If your engine does not need it, you are wasting your money. You will get no better performance either as you engine cannot benefit (unless you adjusted timing via chip or slapped on a supercharger)

kjeeper10 04-20-2012 08:16 PM

Quote:

Originally Posted by OH9JK

My Jeep likes Shell gas too

:cool:

Both Valero and Sunoco the jeep pings. Shell she is quiet :)

aelwero 04-20-2012 10:19 PM

Quote:

Originally Posted by Jurhip (Post 2284797)
I believe the 3.8l has knock control. No modern engine with it should ping regardless of load. If it is, it is a sign something else it not right (tune, plugs, knock s sensor, O2 sensor...)

OP, higher octane does not mean "better". If your engine does not need it, you are wasting your money. You will get no better performance either as you engine cannot benefit (unless you adjusted timing via chip or slapped on a supercharger)

normally I would agree, but I have heard the difference on my 2010 first hand :) It doesn't sound like pre ignition knock though, it actually sounds like valve chatter, which also shouldn't be affected by octane at all, but running higher octane quiets it nonetheless. An oil change will also quiet it down for a few hundred miles.

I haven't tried different gas stations though... might have to shop around and see who has better gas.

DustinLH00 04-20-2012 11:56 PM

Quote:

Originally Posted by aelwero (Post 2285379)
normally I would agree, but I have heard the difference on my 2010 first hand :) It doesn't sound like pre ignition knock though, it actually sounds like valve chatter, which also shouldn't be affected by octane at all, but running higher octane quiets it nonetheless. An oil change will also quiet it down for a few hundred miles.

I haven't tried different gas stations though... might have to shop around and see who has better gas.

I am curious about brand as well. Near me BP, Shell, and Mobil are all very common and readily available. I generally only go to one of the 3.

flyinion 04-21-2012 02:34 AM

When I had my 350Z, one of the guys on the monthly group drives we did in the summer time told me Shell was supposed to be the best. Apparently he and his brother who both had 370's send their oil off to some lab every time they change it and it always gets changed with some kind of "special" oil and one of the tips that they got from their lab guy is that Shell is the best to use. Obviously I can't really say how accurate that is, but I DO get better mpg off of it and the butt dyno likes it as well, but of course the butt dyno is subjective.

Octane ratings, always go with the mfr. recommended unless you're running some kind of special tuning, turbos, supercharged, etc. If you really are having problems on 87 in a non-modified Jeep, something is wrong. Either bad gas, or a mechanical issue.

Mr. Sinister 04-25-2012 11:13 AM

Quote:

Originally Posted by Jurhip (Post 2284797)
I believe the 3.8l has knock control. No modern engine with it should ping regardless of load. If it is, it is a sign something else it not right (tune, plugs, knock s sensor, O2 sensor...)

OP, higher octane does not mean "better". If your engine does not need it, you are wasting your money. You will get no better performance either as you engine cannot benefit (unless you adjusted timing via chip or slapped on a supercharger)

If I were not getting 18/24 for fuel mileage, I might think something was wrong. I also don't seem to have this huge lack of power so many 3.8 owners complain of, mine gets down the road (and up the hills) just fine.


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