Fuel grade - 3.7KJ

[nzoliver]

Hi all!!

What grade of fuel do Jeep say to use and what do you guys use?
We have 91RON and 95 RON and 98RON here. We use the RON octane rating and you guys use PON so..
91RON = 84
95RON = 87
98RON = 90

I normally use our 95.

Thoughts?

 

[Prospect62]

I think most of us use 87 octane (as it is referred to here in the U.S.). That's what Jeep calls for and there's really no advantage to paying more for a higher grade.

 

[ephantmon]

The only time higher octane (89) is recommended is when under load (towing) or operating at consistent high heat (90+ degrees F)

 

[SDLiberty]

The only time higher octane (89) is recommended is when under load (towing) or operating at consistent high heat (90+ degrees F)

So when it's 90+ here San Diego, It's best to run higher octaine? Did not know that???

 

[Marlon_JB2]

Never run anything over 87 Octane in anything.

 

[JJsKJ]

Never run anything over 87 Octane in anything.

Ditto. Never had a problem w/ pinging on the KJ towing or in high heat here in the desert.


now in my Mustang it would be a different story w/ 10.5:1 compression.

 

[Powerslave]

You need to know what octane does. If your engine is NOT knocking and pinging with 87, then STAY there. Basically, the octane rating measures resistance of gasoline and other fuels to detonation (engine knocking) in spark-ignition for internal combustion engines. High-performance engines, typically, have a higher compression ratio, and are more prone to "detonation," so they require the higher octane fuel. A lower-performance engine will not generally perform better with high-octane fuel, since the compression ratio is fixed by the engine design.

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, it causes knocking in the engine (premature ignition). So, detonation is the gasoline igniting spontaneously, just before the plug fires, thus causing the KNOCK you hear. Cars with a knock sensor will have the computer adjust timing to prevent this anyway, so you don't need higher octane really.

So, if your engine runs fine with 87, then don't bother changing to higher octane, there is no reason to.

 

[J-Thompson]

Hi all!!

What grade of fuel do Jeep say to use and what do you guys use?
We have 91RON and 95 RON and 98RON here. We use the RON octane rating and you guys use PON so..
91RON = 84
95RON = 87
98RON = 90

I normally use our 95.

Thoughts?

I like the cheep pon ,some will get it
I never have any problems with the 87 ,can not get any lower

 

[trail rated]

Use 95 RON. If you tow in hot weather then use 98 RON.

 

[Ry' N Jen]

87 Octane works just fine and that's what the owners manual calls for during day to day driving.
If and when we tow something I'll go up 98 Octane.
I don't do fuel additives either, all they do is light up the check engine light and suck more money out of my pocket.

 

[tjkj2002]

Now if you are heavily armored like my KJ is,which is 1500lbs over stock weight,you may want to go higher in octane,it's bassically like towing a 15oolbs trailer.Here in CO we get the choice of 85,87,and mostly 91 octane due to the 6000'+ elevation.I have always had to use premium gas in my KJ to keep it from knocking/pinging,I am chipped though to.Elevation plays a role also,they say the higher you go the lower the octane,not true from personal experiance.The higher the octane level is better suited for crawling in 4low at 10,000'+ elevation,many of the poeple I wheel with have tried premuim also when wheeling at high altitude and it has worked better for them also.

 

[CHUD]

Never run anything over 87 Octane in anything.

Sorry to disagree Marlon, but higher octane is needed for certain high compression engines i.e. SRT 6.1 Hemis. Jeep also recommends 93 octane for the 4.7 HO engine in order to tweak the extra HP, but it's not required.

 

[nzoliver]

Now if you are heavily armored like my KJ is,which is 1500lbs over stock weight,you may want to go higher in octane,it's bassically like towing a 15oolbs trailer.Here in CO we get the choice of 85,87,and mostly 91 octane due to the 6000'+ elevation.I have always had to use premium gas in my KJ to keep it from knocking/pinging,I am chipped though to.Elevation plays a role also,they say the higher you go the lower the octane,not true from personal experiance.The higher the octane level is better suited for crawling in 4low at 10,000'+ elevation,many of the poeple I wheel with have tried premuim also when wheeling at high altitude and it has worked better for them also.

Hi,
Well that figures. My V8 Discovery used to knock under light load where I live (750m up in the mountians) using 95 fuel. Put 98 in it and it was fine. The thing is of course it was a Euro engine which on average require higher octane fuels than US engines.

I'll stick with 95 in my Jeep. Seems very happy.

 

[ephantmon]

FYI- Owner's manual says (regarding fuel grade to use): Mid-grade (89 octane) will give better performance under the following conditions: towing, high temperature, hilly terrain, low humidity

 

[desertkj]

Sorry to disagree Marlon, but higher octane is needed for certain high compression engines i.e. SRT 6.1 Hemis. Jeep also recommends 93 octane for the 4.7 HO engine in order to tweak the extra HP, but it's not required.

You're right. Many of the European cars are also designed to run at higher compressions, so you are losing performance by running lower octane fuels. The same goes with many of the sportbikes I've seen. In fact, I've heard of many people enriching the fuel beyond 91 to get better performance out of the Italian bikes.

 

[desertkj]

Oh, Socks, what do you mean by additives make your check engine light come on? I try to add the Chevron Techron additive they sell at the auto parts stores every 5000 miles and I can usually see an improvement after i use it.

 

[Marlon_JB2]

Sorry to disagree Marlon, but higher octane is needed for certain high compression engines i.e. SRT 6.1 Hemis. Jeep also recommends 93 octane for the 4.7 HO engine in order to tweak the extra HP, but it's not required.

Here's the thing.

I agree with you, but my post was misunderstood. My fault though.

A little clarification:

I've Never run anything over 87 Octane in anything.

And on that note, while we're talking about Chrysler engines...

The 5.7L Hemi *and* the 3.5L V6 both are recommended to be fueled by 89 Octane. Just wanted to throw that out there.

 

[tbaldridge]

I always run premium (93) octane in both of my vehicles. I know this may sound crazy and it could quite possibly just be in my head but my jeep seems to run much better with higher octane in her. I ran a couple tanks of (87) through it and noticed upon acceleration nocking and pinging around. I know the manual states that (87) is recomended but I just feel better putting nothing but the best in her

 

[JeepJeepster]

I think I used 89 once when I was towing... or maybe I just thought about it..

Either way, I regularly use 87 in mine..

 

[Ry' N Jen]

Oh, Socks, what do you mean by additives make your check engine light come on? I try to add the Chevron Techron additive they sell at the auto parts stores every 5000 miles and I can usually see an improvement after i use it.

I bought a tree pack of Wynn's gas treatment and I figured I'd add one bottle to a full tank of regular unleaded. After about 100 km of driving the check engine light came on then off over the remainder of the day.
Called our local Chrysler Jeep dealer and explained the same as above and the service technician told me not to bother with all the so called fuel treatments as most quality fuels already have them added while being manufactured. (He in fact mentioned Chevron with their Techron/Technolene. Shell V power.)
Made appointment and the next day the "Check engine light was no longer illuminated. Took the Liberty by the dealer and Chrysler told me to keep an eye on it and if it lights up again to bring it back in.
Topped up the half tank with Shell and didn't have any more problems.
Another 8 days goes by and I fill up with Chevron this time- a full tank and added another of the gas treatment additives from Chevron this time and within 10 km the check engine light came on again!
Maybe just a coincidence!
After taking the KJ to the dealer a half hour later, they couldn't find anything wrong. And the mechanic said "Don't add fue treatment and other shit to your tank, it's just a total waste of money!"
436 km on the tank of gas and I filled up at Chevron again only this time i didn't add any fuel additives and never saw the "Check engine" light "light up" again.
Since I stopped using the additives (Which only was a waste of my money and NO performance gain what so ever) I hooked up with a close friend of mine who is a Petro Chemical Engineer for Shell. She had some really interesting things to say! Non of them positive I might add!
Snake oil!

Then when you go even a simple Google search on fuel/gasoline additives there are an equal mount of sites both personal/ private and professional that either endorse or denounce the use of said additives.
Here is a good one: http://www.cbc.ca/news/story/2002/05/27/Shellgas_020527.html

So, to finish. I do not believe in these "Additives" and I do not feel, hear, or notice any improvements while having 250 milliliter of "Additive" added to 71,922.823 896 milliliter (19 US gallons) of gasoline.
Seems a little watered down to me, is all!

However if these added ingredients to your fuel do make you notice an improvement in performance or economy, great!
But the money those concoctions cost can be better spent on (or in addition too!) a nice bottle of wine for my wife and I or some good European beer's for Jennifer.