Does lower octane decrease gas milage?
From : mopester
Q: i have 2003 ram hemi w/ 2800 miles. recently i switched to 87 octane because of outrages gas prices in the so. cal area. it seems that im losing about .7 miles per gallon. does this make sense i notice no other performance problem. .
Replies:
From : redneck tookover hell
check. now that the subject has come up i wonder what she is using for octane. roy probably about a 25 year old !!!!!!!! bfg sorry just couldnt resist !!!!! a dyslexic man walks into a bra. .
From : gary glaenzer
yes lower octane = lower mileage less energy per gallon i have 2003 ram hemi w/ 2800 miles. recently i switched to 87 octane because of outrages gas prices in the so. cal area. it seems that im losing about .7 miles per gallon. does this make sense i notice no other performance problem. .
From : jerry
mopester wrote i have 2003 ram hemi w/ 2800 miles. recently i switched to 87 octane because of outrages gas prices in the so. cal area. it seems that im losing about .7 miles per gallon. does this make sense i notice no other performance problem. octane ratings measure a gasolines ability to resist engine knock or as sometimes called pinging and nothing else. a gallon of 87 octane and a gallon of 92 octane both contain the same amount of energy. some higher rated octane gas also contain more chemicals to help resist deposits but all contain a minimum about as required by law. use what your manufactures book calls for. you will not gain in mpg or power by burning a higher rated octane only help reduce pinging if it is present. jerry .
From : hdinny
jerry wrote mopester wrote i have 2003 ram hemi w/ 2800 miles. recently i switched to 87 octane because of outrages gas prices in the so. cal area. it seems that im losing about .7 miles per gallon. does this make sense i notice no other performance problem. octane ratings measure a gasolines ability to resist engine knock or as sometimes called pinging and nothing else. a gallon of 87 octane and a gallon of 92 octane both contain the same amount of energy. some higher rated octane gas also contain more chemicals to help resist deposits but all contain a minimum about as required by law. use what your manufactures book calls for. you will not gain in mpg or power by burning a higher rated octane only help reduce pinging if it is present. jerry he will with the hemi. it calls for 89 but the book also says you can use 87. the computer will keep the engine running right on 87 but it will make more power on 89. i think books in the truck it also calls for 89 if towing. hd in ny .
From : gary glaenzertbone
sounds like somebody got the right tail light bulb in ass backwards not easy but not impossible........ if not that moisture in the lamp housing will do this too 99 ram van 5.9l right signal is clicking and flashing at what seems exactly twice normal rate. left signal is normal speed. the blinker module is in the left dash fuse area and both blinkers appear to be run by the same module. one thing that is maybe a clue i dunno - back when i owned a car whenever i had a trailer hooked up to the car and the trailer tail lights spliced into my cars system the blinkers would blink at twice their normal speed. must have had something to do with the added load. anyway not a thing thats a real serious issue but curious. what does a blinker module cost if that needs replacing what say you .
From : tbone
jerry wrote mopester wrote i have 2003 ram hemi w/ 2800 miles. recently i switched to 87 octane because of outrages gas prices in the so. cal area. it seems that im losing about .7 miles per gallon. does this make sense i notice no other performance problem. octane ratings measure a gasolines ability to resist engine knock or as sometimes called pinging and nothing else. a gallon of 87 octane and a gallon of 92 octane both contain the same amount of energy. some higher rated octane gas also contain more chemicals to help resist deposits but all contain a minimum about as required by law. use what your manufactures book calls for. you will not gain in mpg or power by burning a higher rated octane only help reduce pinging if it is present. jerry he will with the hemi. it calls for 89 but the book also says you can use 87. the computer will keep the engine running right on 87 but it will make more power on 89. i think books in the truck it also calls for 89 if towing. hd in ny while that is true it is doing it by retarding the timing to prevent ping and that is where the power and mileage loss is coming from. actually you performance is a little less and you are compensating by pressing the gas just a little more and probably not even realizing it. -- if at first you dont succeed youre not cut out for skydiving .
From : Annonymousjerry
the 5.9l control system does not have the ability to adjust. for knock as there is no knock sensor system. sometimes it is possible for a bout of knocking to dislodge depoits in the chamber and on the piston which will pass into the exhaust and reduce the hot spots that were intiaiting the knock. as for a high mileage 5.9l or 5.2l which is knocking there have been several tsbs to the dealers informing them of the potential for intake manifold pan and end gaskets allowing oil to leak into the intake manifold. the octane number of oil is extremely low compared to fuel and causes the pinging/knocking. time to find a new dealer! i have a 97 ram 2500 with the 360. i rarely ever hear any pinging and generally run 87 octane. despite what some experts say when i tow my 25 travel trailer i tend to use 89 or 93 octane because it feels like i get a little better performance and fuel economy. this would make sense since todays engine management systems would then provide more advance if it can be done without knock. this summer over a 2-1/2 week period i used my truck for towing more than not and therefore i was continually using at least 89 octane. i stopped for gas along i-84 in ny and got sticker shock at the pump. i filled my near empty tank with 87 octane pulled back onto i-84 with trailer in tow and immediately wondered if i would make it up the next mountain and if i would burn a piston in the process. since the pinging usually is minimized in my truck by turning more rpm i dropped into 2nd gear for a long climb. after that high rpm climb i never heard another knock the rest of the trip! this leads me to believe that the engine management system is in fact capable of adusting the engine for fuel altitiude etc. and mine is doing the dob. i have 85000 miles on mine as well and it has never needed anything but normal maintenace. i do run a complete fuel system additive several times a year. my 98 dodge pings like crazy when i accelerate or when i am just cruising along. i have changed the plugs and plugwires the air cleaner kinds and octanes of gas. no change. any suggestions it has 85000 miles on it and even the dealer is at a loss. -- greg truesdell po box 9907 canoga park ca. 91309 .
From : dennyroy
this is the one that im just gonna keep my mouth shut on.. just walk away mumbling to myself. g no no elmer mumbled bugs just chewed on his carrot..... max and another name gets added to the easter egg list... g denny .
From : jerry
tbone wrote jerry wrote mopester wrote i have 2003 ram hemi w/ 2800 miles. recently i switched to 87 octane because of outrages gas prices in the so. cal area. it seems that im losing about .7 miles per gallon. does this make sense i notice no other performance problem. octane ratings measure a gasolines ability to resist engine knock or as sometimes called pinging and nothing else. a gallon of 87 octane and a gallon of 92 octane both contain the same amount of energy. some higher rated octane gas also contain more chemicals to help resist deposits but all contain a minimum about as required by law. use what your manufactures book calls for. you will not gain in mpg or power by burning a higher rated octane only help reduce pinging if it is present. jerry he will with the hemi. it calls for 89 but the book also says you can use 87. the computer will keep the engine running right on 87 but it will make more power on 89. i think books in the truck it also calls for 89 if towing. hd in ny while that is true it is doing it by retarding the timing to prevent ping and that is where the power and mileage loss is coming from. actually you performance is a little less and you are compensating by pressing the gas just a little more and probably not even realizing it. thats the first time ive heard of a manufacture call for one octane rating but saying you can use another lower if desired. i think if it was me i would then stick with the 89 octane. the extra couple dollars saved on a fill up wouldnt be worth it to me but thats just me. jerry .
From : roy
tbone wrote jerry wrote mopester wrote i have 2003 ram hemi w/ 2800 miles. recently i switched to 87 octane because of outrages gas prices in the so. cal area. it seems that im losing about .7 miles per gallon. does this make sense i notice no other performance problem. octane ratings measure a gasolines ability to resist engine knock or as sometimes called pinging and nothing else. a gallon of 87 octane and a gallon of 92 octane both contain the same amount of energy. some higher rated octane gas also contain more chemicals to help resist deposits but all contain a minimum about as required by law. use what your manufactures book calls for. you will not gain in mpg or power by burning a higher rated octane only help reduce pinging if it is present. jerry he will with the hemi. it calls for 89 but the book also says you can use 87. the computer will keep the engine running right on 87 but it will make more power on 89. i think books in the truck it also calls for 89 if towing. hd in ny while that is true it is doing it by retarding the timing to prevent ping and that is where the power and mileage loss is coming from. actually you performance is a little less and you are compensating by pressing the gas just a little more and probably not even realizing it. thats the first time ive heard of a manufacture call for one octane rating but saying you can use another lower if desired. i think if it was me i would then stick with the 89 octane. the extra couple dollars saved on a fill up wouldnt be worth it to me but thats just me. jerry that is a common thing with gm i believe. the z06 had that sentence in the om i think the wifes eldo does as well. if i can catch up with her ill check. now that the subject has come up i wonder what she is using for octane. roy .
From : hdinny
tbone wrote snipped he will with the hemi. it calls for 89 but the book also says you can use 87. the computer will keep the engine running right on 87 but it will make more power on 89. i think books in the truck it also calls for 89 if towing. hd in ny while that is true it is doing it by retarding the timing to prevent ping and that is where the power and mileage loss is coming from. actually you performance is a little less and you are compensating by pressing the gas just a little more and probably not even realizing it. didnt say it wouldnt. on the other hand an engine with lower compression would gain no benefit from the 89 fuel. and the op was asking about the hemi. i also have one and dont detect any loss in performance for regular street driving with the 87 fuel. for towing the 89 seemed better. after dropping off the trailer and driving with the 89 in the tank i couldnt feel any change in performance after filling up with 87. hd in ny .
From : tbone
tbone wrote snipped he will with the hemi. it calls for 89 but the book also says you can use 87. the computer will keep the engine running right on 87 but it will make more power on 89. i think books in the truck it also calls for 89 if towing. hd in ny while that is true it is doing it by retarding the timing to prevent ping and that is where the power and mileage loss is coming from. actually you performance is a little less and you are compensating by pressing the gas just a little more and probably not even realizing it. didnt say it wouldnt. on the other hand an engine with lower compression would gain no benefit from the 89 fuel. and the op was asking about the hemi. i also have one and dont detect any loss in performance for regular street driving with the 87 fuel. now that would depend on your driving style now wouldnt it/ for towing the 89 seemed better. after dropping off the trailer and driving with the 89 in the tank i couldnt feel any change in performance after filling up with 87. hd in ny if you feel a difference while towing with the 89 then there is a performance change. just because you dont feel it doesnt mean that it is not there. you seem to have a more mellow driving style or at least not pushing it all of the time and since you are probably not pushing the engine very hard during normal driving the octane change will probably not effect you but it does effect the maximum engine performance with the hemi. -- if at first you dont succeed youre not cut out for skydiving .
From : mopester
on fri 26 sep 2003 110211 -0700 mopester wrote i have 2003 ram hemi w/ 2800 miles. recently i switched to 87 octane because of outrages gas prices in the so. cal area. it seems that im losing about .7 miles per gallon. does this make sense i notice no other performance problem. thanks for all the info. i just filled up with 89. i will check it on the next two tanks which shouldnt too long with this truck and let you know if my mpg improved. btw i installed the k&n filter about a 1000 miles ago and didnt notice any mpg improvement. i didnt reset the computer like someone else suggested. i figured the computer would figure it out sooner or later. .
From : hdinny
mopester wrote on fri 26 sep 2003 110211 -0700 mopester wrote i have 2003 ram hemi w/ 2800 miles. recently i switched to 87 octane because of outrages gas prices in the so. cal area. it seems that im losing about .7 miles per gallon. does this make sense i notice no other performance problem. thanks for all the info. i just filled up with 89. i will check it on the next two tanks which shouldnt too long with this truck and let you know if my mpg improved. btw i installed the k&n filter about a 1000 miles ago and didnt notice any mpg improvement. i didnt reset the computer like someone else suggested. i figured the computer would figure it out sooner or later. dont remember if you gave what mpg youre getting now but mine is up to 16 mpg tank mileage. on the trip computer ive registered as much as 19 mpg on a straight level stretch at 55 mph. ive got just over 2000 miles on it. its an 03 qc 1500 with 3.55 gears 2 wheel drive. best darn truck ive ever had aside from my old 78 hevy chevy. hd in ny .
From : wmhj
ok how do you reset the computer on fri 26 sep 2003 110211 -0700 mopester wrote i have 2003 ram hemi w/ 2800 miles. recently i switched to 87 octane because of outrages gas prices in the so. cal area. it seems that im losing about .7 miles per gallon. does this make sense i notice no other performance problem. thanks for all the info. i just filled up with 89. i will check it on the next two tanks which shouldnt too long with this truck and let you know if my mpg improved. btw i installed the k&n filter about a 1000 miles ago and didnt notice any mpg improvement. i didnt reset the computer like someone else suggested. i figured the computer would figure it out sooner or later. .
From : gary bryant
i had a tag hanging on the cigarette lighter in my truck when i bought it a few months ago. i recommended 92/93 octane for the hemi only. it said using a higher octane in the 4.7l may actually cause it to run less efficiently tbone wrote snipped if you feel a difference while towing with the 89 then there is a performance change. just because you dont feel it doesnt mean that it is not there. you seem to have a more mellow driving style or at least not pushing it all of the time and since you are probably not pushing the engine very hard during normal driving the octane change will probably not effect you but it does effect the maximum engine performance with the hemi. of course the engine performance is greater with the 89 just doesnt jump out at you. i wouldnt be surprised if the difference would have to be measured over a quarter mile run. do you happen to have stats to back up your contention just curious as i would like to know how much the actual difference is. as to the difference in towing performance the engine is under a lot of strain so the added hp available is felt. i dont drive in an aggressive manner gas costs too much plus i intend on keeping this truck for many moons. hd in ny .
From : hdinny
gary bryant wrote i had a tag hanging on the cigarette lighter in my truck when i bought it a few months ago. i recommended 92/93 octane for the hemi only. it said using a higher octane in the 4.7l may actually cause it to run less efficiently snipped mine was built in april 03. the manual has 87 to 89 as okay for the hemi and 89 recommended for optimum performance. 92/93 specifically is not recommended for it. maybe yours was built earlier. hd in ny .
From : roy
check. now that the subject has come up i wonder what she is using for octane. roy probably about a 25 year old !!!!!!!! bfg sorry just couldnt resist !!!!! if the 25 year old would only pay some of the bills. g roy .
From : tbone
writes i read a post where someone talked about resetting the computer after changing to a k&n air filter. two questions... 1. how would one do such a thing 2. why would one want to do it 1. disconnect the battery for a few minutes 2. beats the proverbial deficatory waste out of me .
From : tbone
ok how do you reset the computer disconnect the battery for a while. -- if at first you dont succeed youre not cut out for skydiving .
From : jwlbal
im reposting the comments i made on an earlier thread for what its worth i have a 97 ram 2500 with the 360. i rarely ever hear any pinging and generally run 87 octane. despite what some experts say when i tow my 25 travel trailer i tend to use 89 or 93 octane because it feels like i get a little better performance and fuel economy. this would make sense since todays engine management systems would then provide more advance if it can be done without knock. this summer over a 2-1/2 week period i used my truck for towing more than not and therefore i was continually using at least 89 octane. i stopped for gas along i-84 in ny and got sticker shock at the pump. i filled my near empty tank with 87 octane pulled back onto i-84 with trailer in tow and immediately wondered if i would make it up the next mountain and if i would burn a piston in the process. since the pinging usually is minimized in my truck by turning more rpm i dropped into 2nd gear for a long climb. after that high rpm climb i never heard another knock the rest of the trip! this leads me to believe that the engine management system is in fact capable of adusting the engine for fuel altitiude etc. and mine is doing the dob. i have 85000 miles on mine as well and it has never needed anything but normal maintenace. i do run a complete fuel system additive several times a year. i have 2003 ram hemi w/ 2800 miles. recently i switched to 87 octane because of outrages gas prices in the so. cal area. it seems that im losing about .7 miles per gallon. does this make sense i notice no other performance problem. .
From : dennyjwlbal
on sat 27 sep 2003 230105 gmt mac davis mac.davis@comcast.net wrote ill call around on monday but i thought someone in the group might have a ball park figure... wondering if it would be cost effective to change the rear end gears on an 01 dak from 3.55 to 3.9 or whatever if the cost isnt prohibitive id like to have the safety margin and pulling power... but no idea what it would cost.. i picked up a good ring & pinion set on ebay for my van for $25.00. adding new bearings and seals shipping etc. the parts cost was less than $200.00. it took me all day to change it but that included dropping the 30 gal tank on the van. the job does take some special tools. inch/ounce tourque wrench for the pinion bearing preload a special tool to set the diferential bearing preload and a good dial indicator to set the backlash. other than dropping the tank it was a fun job. i would think if you had someone else do it the cost would be in the $800 to $900 range. beekeep why would you have to drop the tank to change the gears another of those east coast things bg denny .
From : mopester
on sat 27 sep 2003 164540 -0700 mopester wrote on fri 26 sep 2003 110211 -0700 mopester wrote i have 2003 ram hemi w/ 2800 miles. recently i switched to 87 octane because of outrages gas prices in the so. cal area. it seems that im losing about .7 miles per gallon. does this make sense i notice no other performance problem. thanks for all the info. i just filled up with 89. i will check it on the next two tanks which shouldnt too long with this truck and let you know if my mpg improved. btw i installed the k&n filter about a 1000 miles ago and didnt notice any mpg improvement. i didnt reset the computer like someone else suggested. i figured the computer would figure it out sooner or later. mine is 03 quad 1500 3.9 gears w/ 20 wheels 2wd and was getting 14mpg and now getting 13.2mpg. about 50-50 city and freeway w/ traffic most of the time. .
From : richardson brian
im doing 11.3mpg consistently on my 03 hemi qc shortbed with 3.92 gears / 20 wheels using amoco 92. just filled up on a tank of hess 89 to see if there is any truth to the rumors so far i do think i feel slightly more power in the seat of my pants. on sat 27 sep 2003 164540 -0700 mopester wrote on fri 26 sep 2003 110211 -0700 mopester wrote i have 2003 ram hemi w/ 2800 miles. recently i switched to 87 octane because of outrages gas prices in the so. cal area. it seems that im losing about .7 miles per gallon. does this make sense i notice no other performance problem. thanks for all the info. i just filled up with 89. i will check it on the next two tanks which shouldnt too long with this truck and let you know if my mpg improved. btw i installed the k&n filter about a 1000 miles ago and didnt notice any mpg improvement. i didnt reset the computer like someone else suggested. i figured the computer would figure it out sooner or later. mine is 03 quad 1500 3.9 gears w/ 20 wheels 2wd and was getting 14mpg and now getting 13.2mpg. about 50-50 city and freeway w/ traffic most of the time. .
From : thehotone
in the midwest ethanol is added to 87 octane to make it 89 wich lowers the btu content of a gallon a fuel causing lowering fuel economy assuming that 87 and 89 have the same btu rating the milage should be the same unless the computer sees pinging and retards the timing to stop the pinging causing lower power and poorer milliage like in vettes and some other cars .