Ever fill up with premium?
#91
Senior Member
Join Date: Jul 2010
Location: Long Island NY
Posts: 997
Likes: 0
Received 1 Like
on
1 Post
Year: 2000
Model: Cherokee
There is so much misinformation in this thread. The only difference between regular and premium fuel is the octane. And octane is the resistance to detonation or burning! Meaning its harder to burn high octane fuels! High octanes do tend to have more additives which may be why some people experience mild improvements. But the higher octane can cause issues with the engine running and burning the fuel efficiently
As for the valve train noise, thats just crazy. The fuel has nothing to do with the valvetrain. There may be other issues though if thats the case.
As for the valve train noise, thats just crazy. The fuel has nothing to do with the valvetrain. There may be other issues though if thats the case.
#92
Junior Member
Join Date: Jul 2010
Location: Illinois
Posts: 73
Likes: 0
Received 0 Likes
on
0 Posts
Year: 1991
Model: Cherokee
Engine: 4.0L I6
There is so much misinformation in this thread. The only difference between regular and premium fuel is the octane. And octane is the resistance to detonation or burning! Meaning its harder to burn high octane fuels! High octanes do tend to have more additives which may be why some people experience mild improvements. But the higher octane can cause issues with the engine running and burning the fuel efficiently
#93
CF Veteran
Join Date: Nov 2009
Location: The Republic of TEXAS
Posts: 8,172
Likes: 0
Received 15 Likes
on
15 Posts
Year: 1998
Model: Cherokee
Engine: 4.0L HO
From what I've experienced, (done numerous compression tests and engine tear downs) the very small mathematical fractional increase in compression ratio that carbon build-up may cause is more than offset by reduced cylinder pressure as an engine ages.
#94
Member
Join Date: Aug 2010
Location: Des Moines, IA
Posts: 127
Likes: 0
Received 0 Likes
on
0 Posts
Year: 2001
Model: Cherokee
Engine: 4.0
No4x4yet, Your opening sentence made me think that you were going to point out some of the 'mis-information' in this thread. Instead you went on to repeat things that have already been said in so many different ways.
#95
Junior Member
Join Date: Jul 2010
Location: Illinois
Posts: 73
Likes: 0
Received 0 Likes
on
0 Posts
Year: 1991
Model: Cherokee
Engine: 4.0L I6
Then it stands to reason, like I said, the compression ratio of an XJ is not high enough to really benefit from premium fuel. I wonder if some people may actually see a decrease in MPG using premium, if the fuel cannot be consumed efficiently.
#97
CF Veteran
Join Date: Aug 2010
Location: Wantage, NJ
Posts: 2,112
Likes: 0
Received 4 Likes
on
3 Posts
Year: 1995
Model: Cherokee
Engine: 4.0 I6
>87 octane fuel is a waste of money in a vehicle that requires 87 octane fuel to run at peak efficiency.
#98
Seasoned Member
Join Date: Oct 2009
Location: Highland IL
Posts: 305
Likes: 0
Received 0 Likes
on
0 Posts
Year: 94
Model: Cherokee
Of course it can. The compression ratio in a jeep is not near what it takes to properly compress and thoroughly combust high test fuel, therefore a loss in power, fuel mileage and a increase in carbon buildup will occur.
>87 octane fuel is a waste of money in a vehicle that requires 87 octane fuel to run at peak efficiency.
>87 octane fuel is a waste of money in a vehicle that requires 87 octane fuel to run at peak efficiency.
#99
I can see a high mileage Xj benefiting from premium but only because of carbon build-up on tops of the pistons and valves causing it to have a higher than stock compression ratio. Seafoam or plain water will cure that problem in an hour though.
In NC the stations are supposed to label their gas as having 10% Ethanol. I know Exxon does but it just says "our gas has 10% Ethanol" I guess that means all of their gas.
I feel running premium in an engine made for regular is a waste of money but man has that not been said already in this thread. lol I know premium fuels usually have more additives I know additives can help quiet engine noises. My facts to back up that statement? Leaded fuel. Why did they use leaded fuel? To keep the valves from beating themselves into the valve seats.
CLint
In NC the stations are supposed to label their gas as having 10% Ethanol. I know Exxon does but it just says "our gas has 10% Ethanol" I guess that means all of their gas.
I feel running premium in an engine made for regular is a waste of money but man has that not been said already in this thread. lol I know premium fuels usually have more additives I know additives can help quiet engine noises. My facts to back up that statement? Leaded fuel. Why did they use leaded fuel? To keep the valves from beating themselves into the valve seats.
CLint
#100
CF Veteran
Join Date: Aug 2010
Location: Wantage, NJ
Posts: 2,112
Likes: 0
Received 4 Likes
on
3 Posts
Year: 1995
Model: Cherokee
Engine: 4.0 I6
I can see a high mileage Xj benefiting from premium but only because of carbon build-up on tops of the pistons and valves causing it to have a higher than stock compression ratio. Seafoam or plain water will cure that problem in an hour though.
In NC the stations are supposed to label their gas as having 10% Ethanol. I know Exxon does but it just says "our gas has 10% Ethanol" I guess that means all of their gas.
I feel running premium in an engine made for regular is a waste of money but man has that not been said already in this thread. lol I know premium fuels usually have more additives I know additives can help quiet engine noises. My facts to back up that statement? Leaded fuel. Why did they use leaded fuel? To keep the valves from beating themselves into the valve seats.
CLint
In NC the stations are supposed to label their gas as having 10% Ethanol. I know Exxon does but it just says "our gas has 10% Ethanol" I guess that means all of their gas.
I feel running premium in an engine made for regular is a waste of money but man has that not been said already in this thread. lol I know premium fuels usually have more additives I know additives can help quiet engine noises. My facts to back up that statement? Leaded fuel. Why did they use leaded fuel? To keep the valves from beating themselves into the valve seats.
CLint
Additives only AID in cleaning, they do not quiet any mechanical part.
#101
Senior Member
Join Date: Jul 2010
Location: Long Island NY
Posts: 997
Likes: 0
Received 1 Like
on
1 Post
Year: 2000
Model: Cherokee
Agreed..the octane rating is, more precisley, the percentage of the hydrocarbon chain octane in the fuel. So 87 octane has 87%octane/13%heptane, and so on. Octane is more resistant to detonation than heptane, so the higher the octane concentration, the more the fuel can be compressed before it combusts. For XJs, the compression ratio of a low-mileage or 'clean' engine is too low to really get any benefit from high octane gas. Older, gunked up engines will have a higher compression ratio with age and buildup of crap so you might see improvement using premium fuel, but using additives/detergents would actually then defeat the purpose of using higher octane fuel.
There is way too much misinformation to cover it all, but octane rating is alot simplier than people think. I really covered all there is to cover regarding octane ratings. And being that higher octane takes more heat and pressure to burn the low the octane you can run the better.
#102
CF Veteran
Join Date: Nov 2009
Location: The Republic of TEXAS
Posts: 8,172
Likes: 0
Received 15 Likes
on
15 Posts
Year: 1998
Model: Cherokee
Engine: 4.0L HO
Go back to page 1 of this thread.......there's claims of 6-7 mpg increase when using premium. Everything I've read and info links I posted beg to differ. My post #13 on page 1.
Premium better than regular?.........the myths just keep on keepin' on. At only 8.8:1 compression for the XJ 4.0, a lawn mower probably has more. I'm still looking for valid info (not opinions) that says premium is better for, improves mileage, makes the engine quieter, even though the owners manual says regular is fine. Someone help me out here.
http://www.consumerenergycenter.org/...s_premium.html
http://www.cartalk.com/content/featu...questions.html
http://www.straightdope.com/columns/...nd-regular-gas
http://www.usatoday.com/money/autos/...emiumgas_x.htm
http://www.epinions.com/content_2346164356
http://www.edmunds.com/advice/fuelec...3/article.html
http://www.caranddriver.sg/features/...emium_-feature
http://www.cartalk.com/content/featu...ium/myths.html
http://www.associatedcontent.com/art...n_premium.html
http://en.wikipedia.org/wiki/Gasoline
Premium better than regular?.........the myths just keep on keepin' on. At only 8.8:1 compression for the XJ 4.0, a lawn mower probably has more. I'm still looking for valid info (not opinions) that says premium is better for, improves mileage, makes the engine quieter, even though the owners manual says regular is fine. Someone help me out here.
http://www.consumerenergycenter.org/...s_premium.html
http://www.cartalk.com/content/featu...questions.html
http://www.straightdope.com/columns/...nd-regular-gas
http://www.usatoday.com/money/autos/...emiumgas_x.htm
http://www.epinions.com/content_2346164356
http://www.edmunds.com/advice/fuelec...3/article.html
http://www.caranddriver.sg/features/...emium_-feature
http://www.cartalk.com/content/featu...ium/myths.html
http://www.associatedcontent.com/art...n_premium.html
http://en.wikipedia.org/wiki/Gasoline
#103
I can see where premium would lower the chances of the pre-igniton or detonation in an engine in this shape or condition.
I have used premium in engines with low compression from the factory and never saw any increase in fuel mileage.
Was the lead in the old leaded fuel called an additive? I don't know. I do know it aided a mechanical part by keeping the valves from beating themselves into the heads.
clint
#104
CF Veteran
Join Date: Dec 2009
Location: Harleysville, PA
Posts: 2,091
Likes: 0
Received 1 Like
on
1 Post
Year: 1998
Model: Cherokee
Engine: 4.0L I6 Powertech
my other jeep's owners manual says: when its humid, heavily loaded, or hilly terrain etc. to use mid grade! now idk if its the same for mine cause i dont have an owners manual but if someone does just see what it has to say!
#105
Member
Thread Starter
Join Date: Jun 2010
Location: Columbus, OH
Posts: 113
Likes: 0
Received 1 Like
on
1 Post
Year: 1996
Model: Cherokee
Engine: 4.0 of course
There is so much misinformation in this thread. The only difference between regular and premium fuel is the octane. And octane is the resistance to detonation or burning! Meaning its harder to burn high octane fuels! High octanes do tend to have more additives which may be why some people experience mild improvements. But the higher octane can cause issues with the engine running and burning the fuel efficiently
As for the valve train noise, thats just crazy. The fuel has nothing to do with the valvetrain. There may be other issues though if thats the case.
As for the valve train noise, thats just crazy. The fuel has nothing to do with the valvetrain. There may be other issues though if thats the case.