mpg on 93 vs 89 octane gas
03-22-12, 08:18 PM
#1
Pole Position
Thread Starter
mpg on 93 vs 89 octane gas
Summary
93 octane Premium: 29.6 mpg
89 octane Mid-grade: 29.4 mpg
Conclusion: no difference
I have recorded the miles and gallons for almost every tank of gas for my 2009 IS 250 RWD auto since I bought it brand new on 6/30/2009. That is almost 100 tanks and currently a bit past 35k miles. I always calculate my mpg using miles driven divided by gallons pumped in to fill.
My driving style is very relaxed. I do a lot of highway miles, but even when I'm in the city, I can get close to 30 mpg by timing traffic and coasting. I live in Florida and the roads are mostly flat here.
Until Nov 2011 and 33k miles, I always used 93 octane. The mpg for these first 90 or so tanks was 29.6 mpg.
In Dec 2011, I decided to switch to 89 octane. My driving patterns remained the same. One difference I can think of is it is during the winter. I have done 6 tanks and 2,300 miles on 89 octane. The mpg was 29.4 mpg.
Probably if you do the stats and work out the standard error and confidence intervals, you will find no significant difference between my mpg on 93 vs 89 octane gas.
I haven't noticed any knocking. But I don't drive hard and the automatic does not put the engine in situations likely to generate knocking--low rpm, high load.
So, especially with gas prices increasing, I will continue my experiment on 89 octane gas through the summer, and report the results here.
93 octane Premium: 29.6 mpg
89 octane Mid-grade: 29.4 mpg
Conclusion: no difference
I have recorded the miles and gallons for almost every tank of gas for my 2009 IS 250 RWD auto since I bought it brand new on 6/30/2009. That is almost 100 tanks and currently a bit past 35k miles. I always calculate my mpg using miles driven divided by gallons pumped in to fill.
My driving style is very relaxed. I do a lot of highway miles, but even when I'm in the city, I can get close to 30 mpg by timing traffic and coasting. I live in Florida and the roads are mostly flat here.
Until Nov 2011 and 33k miles, I always used 93 octane. The mpg for these first 90 or so tanks was 29.6 mpg.
In Dec 2011, I decided to switch to 89 octane. My driving patterns remained the same. One difference I can think of is it is during the winter. I have done 6 tanks and 2,300 miles on 89 octane. The mpg was 29.4 mpg.
Probably if you do the stats and work out the standard error and confidence intervals, you will find no significant difference between my mpg on 93 vs 89 octane gas.
I haven't noticed any knocking. But I don't drive hard and the automatic does not put the engine in situations likely to generate knocking--low rpm, high load.
So, especially with gas prices increasing, I will continue my experiment on 89 octane gas through the summer, and report the results here.
Last edited by Toymota; 03-24-12 at 07:35 PM. Reason: Added summary
03-22-12, 08:54 PM
#2
I have recorded the miles and gallons for almost every tank of gas for my 2009 IS 250 RWD auto since I bought it brand new on 6/30/2009. That is almost 100 tanks and currently a bit past 35k miles. I always calculate my mpg using miles driven divided by gallons pumped in to fill.
My driving style is very relaxed. I do a lot of highway miles, but even when I'm in the city, I can get close to 30 mpg by timing traffic and coasting. I live in Florida and the roads are mostly flat here.
Until Nov 2011 and 33k miles, I always used 93 octane. The mpg for these first 90 or so tanks was 29.6 mpg.
In Dec 2011, I decided to switch to 89 octane. My driving patterns remained the same. One difference I can think of is it is during the winter. I have done 6 tanks and 2,300 miles on 89 octane. The mpg was 29.4 mpg.
Probably if you do the stats and work out the standard error and confidence intervals, you will find no significant difference between my mpg on 93 vs 89 octane gas.
I haven't noticed any knocking. But I don't drive hard and the automatic does not put the engine in situations likely to generate knocking--low rpm, high load.
So, especially with gas prices increasing, I will continue my experiment on 89 octane gas through the summer, and report the results here.
My driving style is very relaxed. I do a lot of highway miles, but even when I'm in the city, I can get close to 30 mpg by timing traffic and coasting. I live in Florida and the roads are mostly flat here.
Until Nov 2011 and 33k miles, I always used 93 octane. The mpg for these first 90 or so tanks was 29.6 mpg.
In Dec 2011, I decided to switch to 89 octane. My driving patterns remained the same. One difference I can think of is it is during the winter. I have done 6 tanks and 2,300 miles on 89 octane. The mpg was 29.4 mpg.
Probably if you do the stats and work out the standard error and confidence intervals, you will find no significant difference between my mpg on 93 vs 89 octane gas.
I haven't noticed any knocking. But I don't drive hard and the automatic does not put the engine in situations likely to generate knocking--low rpm, high load.
So, especially with gas prices increasing, I will continue my experiment on 89 octane gas through the summer, and report the results here.
03-22-12, 09:02 PM
#3
I guess for what you've compared, gas mileage, it's good stats. But still leaves other questions unanswered about long term use of lower grade gasoline. Is price of gas your only driving factor to be making the gas Downgrade? If so, I'll never really understand how people can't afford $5 or so more per tank but still drive a lexus
Trending Topics
03-23-12, 05:00 AM
#9
When I push the fuel button(little gas tank emblem) in my 2011 250 ISC, the little door pops open.
INSIDE that door is a sign that says PREMIUM UNLEADED FUEL ONLY.....
I owned a 1997 Maxima years ago. It also required Premium Gas. I tried Regular when I hit 150K. 5000 miles later, the Check engine light illuminates. Guess what the diagnosis was? KNOCK SENSOR.
We went immediately back to Premium and it never happened again. I sold the car at 230k after owning 10 years.
Driving 15000 miles a year, assuming Premium Gas is 20 cents higher than Regular, it would cost you 8 dollars a month more to use regular. That is one happy meal AND that is assuming the gas mileage is the same for regular and premium which is absolutely not true. You will get at least 2 - 3 mpg better with premium.
When we 1st bought our Lexus, the gpm dropped after 3000 miles 3 mpg. FINALLY after 2x of filling up, My wife realized she was using 87 octane instead of 93 by habit. She drives 400 miles a week mostly highway to work.
Love your Car and follow the Gas Cap instructions.
INSIDE that door is a sign that says PREMIUM UNLEADED FUEL ONLY.....
I owned a 1997 Maxima years ago. It also required Premium Gas. I tried Regular when I hit 150K. 5000 miles later, the Check engine light illuminates. Guess what the diagnosis was? KNOCK SENSOR.
We went immediately back to Premium and it never happened again. I sold the car at 230k after owning 10 years.
Driving 15000 miles a year, assuming Premium Gas is 20 cents higher than Regular, it would cost you 8 dollars a month more to use regular. That is one happy meal AND that is assuming the gas mileage is the same for regular and premium which is absolutely not true. You will get at least 2 - 3 mpg better with premium.
When we 1st bought our Lexus, the gpm dropped after 3000 miles 3 mpg. FINALLY after 2x of filling up, My wife realized she was using 87 octane instead of 93 by habit. She drives 400 miles a week mostly highway to work.
Love your Car and follow the Gas Cap instructions.
03-23-12, 05:02 AM
#10
Pole Position
Thread Starter
Yeah, this is just an experiment. I think a lot of people just believe what other people say without testing or having any real evidence. Things like "you will lose 5mpg by using lower octane gas", "your engine will knock the pistons to hell", "winter blend gas will kill your mileage" or on another topic "you should use synthetic oil and change it every 3,000 miles".... So I'm just curious and like to test things out for myself. It's not about the money. I have a six-figure job and the difference between 93 and 89 is 15 cents/gal here so only around $2.40/tank.
03-23-12, 05:27 AM
#11
Yeah, this is just an experiment. I think a lot of people just believe what other people say without testing or having any real evidence. Things like "you will lose 5mpg by using lower octane gas", "your engine will knock the pistons to hell", "winter blend gas will kill your mileage" or on another topic "you should use synthetic oil and change it every 3,000 miles".... So I'm just curious and like to test things out for myself. It's not about the money. I have a six-figure job and the difference between 93 and 89 is 15 cents/gal here so only around $2.40/tank.
Last edited by heyarms; 03-23-12 at 08:18 AM.
03-23-12, 06:19 AM
#12
Rookie
iTrader: (1)
Join Date: Jan 2011
Location: Virginia
Posts: 51
Likes: 0
Received 0 Likes
on
0 Posts
Yeah, this is just an experiment. I think a lot of people just believe what other people say without testing or having any real evidence. Things like "you will lose 5mpg by using lower octane gas", "your engine will knock the pistons to hell", "winter blend gas will kill your mileage" or on another topic "you should use synthetic oil and change it every 3,000 miles".... So I'm just curious and like to test things out for myself. It's not about the money. I have a six-figure job and the difference between 93 and 89 is 15 cents/gal here so only around $2.40/tank.
.
03-23-12, 06:32 AM
#13
I guess for what you've compared, gas mileage, it's good stats. But still leaves other questions unanswered about long term use of lower grade gasoline. Is price of gas your only driving factor to be making the gas Downgrade? If so, I'll never really understand how people can't afford $5 or so more per tank but still drive a lexus
BUT GIVE ME MY VENTI LATTE!
03-23-12, 06:34 AM
#14
thanks!
03-23-12, 06:48 AM
#15
Pole Position
Join Date: Dec 2011
Location: Texas
Posts: 281
Likes: 0
Received 0 Likes
on
0 Posts
Interesting thread. I tried a tank or two of 87 octane, but the power seemed to lag (could be placebo effect). I am not convinced lower octane would ruin your engine, but agree using the recommended is really the best answer.
Side Note - Not sure why this is such an emotional topic. More conversation - less emotion/personal attacks please.
Side Note - Not sure why this is such an emotional topic. More conversation - less emotion/personal attacks please.