Fuel Grade and gas mileage PSA

[jessieomc]

Since I bought my civic in December I have been using regular ol 87 octane fuel. I was averaging around 24-26 mpg with my daily in town driving but I was slightly butthurt that everyone else seemed to be getting around 30 mpg.

Decided to switch to 89 my last 2 fill ups and now I'm easily getting 30-32 mpg! That's a huge difference in my opinion, so from now on I'll be using at least 89 or better.

I'm tempted to try using premium the next 2 tanks and see if it makes that much more difference!

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[dc2turbo]

Since I bought my civic in December I have been using regular ol 87 octane fuel. I was averaging around 24-26 mpg with my daily in town driving but I was slightly butthurt that everyone else seemed to be getting around 30 mpg.

Decided to switch to 89 my last 2 fill ups and now I'm easily getting 30-32 mpg! That's a huge difference in my opinion, so from now on I'll be using at least 89 or better.

I'm tempted to try using premium the next 2 tanks and see if it makes that much more difference!

weather plays a factory in your mpg too

 

[jessieomc]

weather plays a factory in your mpg too

Agreed- I'm definitely not a fuel economy expert, but over the past month or so the weather here has ranged from 80F to 45F on any given day so I feel like thats not quite as much of a factor- especially for a 5 MPG difference.

 

[bahndrvr]

Agreed- I'm definitely not a fuel economy expert, but over the past month or so the weather here has ranged from 80F to 45F on any given day so I feel like thats not quite as much of a factor- especially for a 5 MPG difference.

I have an Si and have seen similar however I have never used below 89 With the 93 here winter blend I'm getting around 36mpg at 80 mpg - with the summer blend and Marathon fuel I was seeing 39 consistent for a while, but I could tell when they switched to the winter blend here Should be getting the better fuel blend soon and hoping to see over 40 mpg with the Si due to being over 15k miles now.

 

[TakeoSato]

Since I bought my civic in December I have been using regular ol 87 octane fuel. I was averaging around 24-26 mpg with my daily in town driving but I was slightly butthurt that everyone else seemed to be getting around 30 mpg.

Decided to switch to 89 my last 2 fill ups and now I'm easily getting 30-32 mpg! That's a huge difference in my opinion, so from now on I'll be using at least 89 or better.

I'm tempted to try using premium the next 2 tanks and see if it makes that much more difference!

I mostly drive city and I have been getting around 29mpg. I use 87, but now ill have to try 89 and see ^_^!

 

[kasian]

I mostly drive city and I have been getting around 29mpg. I use 87, but now ill have to try 89 and see ^_^!

I also drive mostly city in CA and also get around 29~30mpg every tank, depending on how long I drive on highways with my family during weekends. Meanwhile I keep refilling at Costco and I tried both regular (87) and premium (91) gas. No noticeable mpg difference yet.
Mine is a HB Ex.

 

[VarmintCong]

Since I bought my civic in December I have been using regular ol 87 octane fuel. I was averaging around 24-26 mpg with my daily in town driving but I was slightly butthurt that everyone else seemed to be getting around 30 mpg.

Decided to switch to 89 my last 2 fill ups and now I'm easily getting 30-32 mpg! That's a huge difference in my opinion, so from now on I'll be using at least 89 or better.

I'm tempted to try using premium the next 2 tanks and see if it makes that much more difference!

I was just gonna post the opposite. I've been running 93 octane in my 6MT Sport hatch for its entire life. I get a max of about 42-43. Just tried a tank of 87, and on a 160 mile highway trip, I got 46.2 mpg, that's a record for my car, and there was traffic, although sometimes that helps cause you drive slower, not 75-78 mph.

I had previously tried 87 once or twice but seemed like I got worse gas mileage, and I've been using Shell cause that seemed to get me higher mpg.

Sometimes you see a large change in mileage around season changes - like they switch to summer formulation when it's still cold out, or vice versa. I'll see if it lasts.

 

[a c i d.f l y]

My 2.0 gets crap mileage using 93 octane, around 20-25. 87 octane nets the best mileage. With 87 and long distance driving I get around 40-44mpg. Also being in Texas, I've noticed mileage suffers above 75mph. On the Texas autobahn (130) at 85-90 I only get around 30mpg.

 

[syncro87]

Two reasons for your MPG increase, neither of which are octane related.

Weather. Winter weather takes a significant toll on MPG. Your car runs rich at startup, until the engine reaches operating temp. This takes longer when it is 20 degrees F or 40 degrees F than it does at 50 or 60.

Seasonal fuel blends. Many areas of the USA have different fuel blends at different times of the year for emissions reasons.



The above probably account for 95% of your MPG increase. 87 to 89 would impact it nearly zero.

There is one typical case where premium fuel can have a significant impact. In some areas, you can buy premium fuel that is ethanol free. Pure gasoline will typically net you a small increase of 3-5% versus gasoline with <10% ethanol. This is due to the lack of ETOH, not the octane value of the fuel.

 

[AndyAndromeda-AUS]

Since I bought my civic in December I have been using regular ol 87 octane fuel. I was averaging around 24-26 mpg with my daily in town driving but I was slightly butthurt that everyone else seemed to be getting around 30 mpg.

Decided to switch to 89 my last 2 fill ups and now I'm easily getting 30-32 mpg! That's a huge difference in my opinion, so from now on I'll be using at least 89 or better.

I'm tempted to try using premium the next 2 tanks and see if it makes that much more difference!

The real question would be mathematically are you saving anything, if the fuel costs more to go further... Is it worth it.

 

[jessieomc]

So based on replies Im now convinced that there are too many variables to account for and just because I'm getting better mileage doesn't mean someone else's car will.

Weather
Seasonal fuel blend
Driving habits
Transmission type
ETOH content
Etc....

Either way, Ive personally noticed performance differences in my own car and feel like the little extra I'll pay for the 89 octane is worth it.

 

[syncro87]

So based on replies Im now convinced that there are too many variables to account for and just because I'm getting better mileage doesn't mean someone else's car will.

Weather
Seasonal fuel blend
Driving habits
Transmission type
ETOH content
Etc....

Either way, Ive personally noticed performance differences in my own car and feel like the little extra I'll pay for the 89 octane is worth it.

https://en.wikipedia.org/wiki/Confirmation_bias

It's a somewhat free country. What is important is what makes you happy with your car. If it makes you feel better to run 89, by all means. What some joker like me on an internet forum thinks about your decision matters not.

 

[FearTheH]

Going from Roanoke VA to Miami FL via 77 and 95 and running on 93(92 where 93 not available) shell only and cruising between 80 and 100 I was averaging between 42 and 44 mpg and getting roughly 480 to 500 miles per tank. So freaking nice!
2018 Civic Sport 6MT Ktuner stage 2 base map.

 

[IDriveACivic]

Hmm... I get 29 - 32 MPG on mixed driving (40/60 split city/hwy split). I've added 89 instead of 87 on a couple of occasions, but I cannot conclusively say that one is better than the other in terms of performance or efficiency. This will remain to be my position until someone does extensive, controlled testing:

- Same driving habits
- Same route
- Same weather conditions

Subjectively speaking, I won't say 89 gives better performance, unless someone performs a blind test

 

[rraayy3]

It costs $40 to fill up with Premium 93 octane

I haven’t used anything less and I don’t think I will

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