[Dr. Toboggan]

If Honda says I can run 87 then….87 it is. Now, most of you guys are in boost all the time, I’m practically never in boost.

We use 87 but that’s because of the price. I’ll talk to my service advisor who in turn will ask the experienced technician. If needed then I will use higher but because the mpg is always between 38 and 40 when my wife drives I doubt that she runs it boosted. Now myself, the few times a week that I drive it I run the shit out of it.

 

[Chaz]

We use 87 but that’s because of the price. I’ll talk to my service advisor who in turn will ask the experienced technician. If needed then I will use higher but because the mpg is always between 38 and 40 when my wife drives I doubt that she runs it boosted. Now myself, the few times a week that I drive it I run the shit out of it.

As someone who works in service, they put 87 rates because it’s easier to sell a car that does not need premium gas,

and your service advisor could tell you the moon is made of cheese and you would probably believe it lol

 

[Dr. Toboggan]

and your service advisor could tell you the moon is made of cheese and you would probably believe it lol

I’ve known him for 4 years and the master technician for over 10 years and will trust them over some anonymous poster on an internet forum.

I want the answer to be that 87 octane is okay, like I said due to price, but if necessary I will use higher.

 

[cleanneon98]

Si needs premium while the others do not due to different tuning. You gain nothing filling your EX/Sport Touring with premium, the N/A sport models with 2.0L would be even a bigger waste

 

[11406]

and your service advisor could tell you the moon is made of cheese and you would probably believe it lol

 

[sixty3]

Si needs premium while the others do not due to different tuning. You gain nothing filling your EX/Sport Touring with premium, the N/A sport models with 2.0L would be even a bigger waste

If the Si needed higher than 87 then it would not say 87 required. The car literally has a sticker near the fuel filler that says 87.

 

[Chaz]

If the Si needed higher than 87 then it would not say 87 required. The car literally has a sticker near the fuel filler that says 88.

It says 87 so the car is easier to sell, a car that needs premium gas is harder to sell.

can it survive in 87? Yes definitely! But will your car last longer on 93? Definitely

 

[11406]

It says 87 so the car is easier to sell, a car that needs premium gas is harder to sell.

can it survive in 87? Yes definitely! But will your car last longer on 93? Definitely

2025 Civic Owners manual pg. 635 states manual transmission models require 91 or higher octane.

 

[sixty3]

Did they change something between 2022 and 2025?

My 2022 si, with 229,538 miles, says right on the gas door, 87 minimum.

 

[sixty3]

It says 87 so the car is easier to sell, a car that needs premium gas is harder to sell.

can it survive in 87? Yes definitely! But will your car last longer on 93? Definitely

How long will it survive on 87? 93?

 

[Cueyo]

I'm gonna bet it's negligible, people forget that engines adapt to different octanes. If you have a logging software or ktuner v2 you can see in real-time how the car goes from running lean/rich to as close to in between as it can get. My engine was choking for at least 3 months and knock control did its job. It would do the same if your octane was different, though it's not ideal given how lower octane combusts with less pressure.

 

[rokonman]

Turbo engines rated for 87 octane will live forever on regular. Today’s control modules will happily suck out timing and boost to protect those pistons. With the allowance I get from my wife it’s exactly what my VW Alltrack got when its racechip was turned off. That said, Turbo engines definitely make more power on premium fuel as then their allowed full boost and timing.

 

[11406]

Did they change something between 2022 and 2025?

My 2022 si, with 229,538 miles, says right on the gas door, 87 minimum.

With 230K, just keep doing what you're doing. I bet that gas door is used on all Civics with the same sticker.

 

[Dr. Toboggan]

My EX doesn’t have a sticker, we have always put 87 octane and there are no problems so far but I don’t want to find out the hard way.

 

[Chaz]

My EX doesn’t have a sticker, we have always put 87 octane and there are no problems so far but I don’t want to find out the hard way.

If you drive conservatively I would say 87 is fine for your ex, but for the si I would put premium gas in as the manual recommends cuz it pushes more boost

 

[sixty3]

If you drive conservatively I would say 87 is fine for your ex, but for the si I would put premium gas in as the manual recommends cuz it pushes more boost

Doesn’t a regular 1.5 civic have like 16.5 pounds of boost?
Isn’t that only 1.3 pounds less than an Si?

It isn’t as if a regular 1.5 civic had 8 pounds of boost and an Si had like 45 pounds. 16.5 and 17.8 aren’t exactly 10s of boost apart from each other.

 

[Chaz]

Doesn’t a regular 1.5 civic have like 16.5 pounds of boost?
Isn’t that only 1.3 pounds less than an Si?

It isn’t as if a regular 1.5 civic had 8 pounds of boost and an Si had like 45 pounds. 16.5 and 17.8 aren’t exactly 10s of boost apart from each other.

The turbo is bigger on the si so it’s running more boost even if it had the same amount of map pressure. Turbo boost pressure does not mean as much as the actual size of the turbo.

I bet the si has more aggressive timing as well.

these cars are smart and learn to adjust timing the octane you use, so the chances of lspi even if you use 87 are low but if you have an si I would use premium gas still.

 

[dxdxto]

My understanding is that the main culprit for head gasket blowing is the LSPI (Low Speed Pre Ignition), affecting many (all?) turbo-charged + direct-injected gasoline engines. Higher octane fuel and good oil can greatly reduce the problem.

I watch some TCCN every now and then, and not that long he discussed the same issue with Highlanders. He said that every time he gets a Highlander with a blown head gasket it has the original factory coolant and that whatever the shortcomings of the design are it's the lack of maintenance that does them in.

 

[sixty3]

The turbo is bigger on the si so it’s running more boost even if it had the same amount of map pressure. Turbo boost pressure does not mean as much as the actual size of the turbo.

I bet the si has more aggressive timing as well.

these cars are smart and learn to adjust timing the octane you use, so the chances of lspi even if you use 87 are low but if you have an si I would use premium gas still.

Is the turbo bigger in an Si compared to a normal 1.5 civic? I’ve read they are the exact same turbo on both cars.

 

[rallyred25civicsi]

I am a high mileage 1.5 guy.

2022 Si bought November 22 of 2022. Currently has 228,XXX.

The only issue I have is the steering issue, there is a recall for that.

Other than that, change the wet stuffs, filters and occasionally the plugs and keep on keeping on.

swe