11th Gen Civic Forum banner
1 - 8 of 8 Posts

·
Registered
Joined
·
58 Posts
Discussion Starter · #1 ·
Hello, I know the Touring calls for "87 octane or above" but I wanted to make sure 89 octane on it's own, or mixed with 87 would be okay. I've heard in the past that it's detrimental to put 93 octane in a car that calls for 87. Thanks for any well-informed help. I'm sure I'll usually put 87, but there is a gas station by me that has 89.
 

·
Registered
22 Civic Hatchback Sport Touring
Joined
·
26 Posts
Hello, I know the Touring calls for "87 octane or above" but I wanted to make sure 89 octane on it's own, or mixed with 87 would be okay. I've heard in the past that it's detrimental to put 93 octane in a car that calls for 87. Thanks for any well-informed help. I'm sure I'll usually put 87, but there is a gas station by me that has 89.

If it calls for 87 or above, how would it be detrimental to put 93? I’m curious.
 

·
Registered
2022 Civic Hatchback ST 6MT in PWP
Joined
·
203 Posts
If it calls for 87 or above, how would it be detrimental to put 93? I’m curious.
Having money good
Not having money bad
Spending extra money on something is not having money you would otherwise have
If that extra money gets you something extra you wouldn't get otherwise, maybe that's good
But if spending extra money gets you nothing extra, that is bad

89 Octane fuel is nearly utterly pointless as pretty much nothing is ever tuned for it. I have heard legends of specific makes and models of cars of years gone by (Volvo? Oldsmobile?) that had a factory spec of "89 octane minimum", but never seen one. It's not like getting 2% milk instead of 1% or whole milk.

Nowadays, with all the electronic tech in cars, using "regular" lower octane fuel (87) in a car that "requires" 91 or 93 octane typically will not damage the engine; the ECU will detect it and retard timing so you lose power and maybe efficiency (fuel economy) versus what it would optimally do with the kind of fuel it was tuned for

But the reverse is also true - a car that is NOT tuned to do something special with higher octane fuel, will do nothing special with higher octane fuel. Meaning you just paid more per gallon and bought into "premium detergent additives" as the benefit (which you could buy in a bottle of Techron or something every few fill-ups, if you wanted to do that).

As for octane below 87, that is not a good idea in general, I think at very high altitudes they sell 85 octane as a cheaper "regular" fuel based on the idea that the lower atmospheric pressure makes 85 octane "run like" 87 or something, but of course as soon as you drive around somewhere lower in elevation you might be in trouble, as ECUs are not likely going to be tuned (programmed) for octane lower than 87
 

·
Registered
Joined
·
718 Posts
Hello, I know the Touring calls for "87 octane or above" but I wanted to make sure 89 octane on it's own, or mixed with 87 would be okay. I've heard in the past that it's detrimental to put 93 octane in a car that calls for 87. Thanks for any well-informed help. I'm sure I'll usually put 87, but there is a gas station by me that has 89.
I've mixed gas before with higher grades and I've never had any issues with the car afterwards. For any vehicle as long as the gas grades are either the recommended grade or higher you'll be fine. Never use gas below what's recommended.

That being said, adding higher grade gas than what's recommended to a stock car doesn't really do much.

 

·
Registered
2022 Civic Hatchback ST 6MT in PWP
Joined
·
203 Posts
I've mixed gas before with higher grades and I've never had any issues with the car afterwards. For any vehicle as long as the gas grades are either the recommended grade or higher you'll be fine. Never use gas below what's recommended.

That being said, adding higher grade gas than what's recommended to a stock car doesn't really do much.
Actually that's worth asking as I am not 100% sure of the answer

Let's say your car is tuned for 91 octane, and is modern enough for the ECU to detect 87 octane to retard the timing for a (say) 10% loss in power

Is it a linear thing, i.e., if you did use 89 octane, or had half a tank of 91 in there when you refilled to full with 87, would the ECU interpolate the timing and result in somewhere between 0% and 10% loss in power from its optimal tune at 91 octane?
 

·
Registered
Joined
·
1,191 Posts
Actually that's worth asking as I am not 100% sure of the answer

Let's say your car is tuned for 91 octane, and is modern enough for the ECU to detect 87 octane to retard the timing for a (say) 10% loss in power

Is it a linear thing, i.e., if you did use 89 octane, or had half a tank of 91 in there when you refilled to full with 87, would the ECU interpolate the timing and result in somewhere between 0% and 10% loss in power from its optimal tune at 91 octane?
With BMWs you can apparently run any octane. From BMW Blog:
The way engineers help you avoid pings and knocks is by using an octane sensor. This sensor detects the type of fuel you're running and retards the spark timing in your engine so there's little to no risk of detonation if fuel might be less stable than recommended.
 

·
Registered
2022 Honda Civic Touring
Joined
·
43 Posts
Hello, I know the Touring calls for "87 octane or above" but I wanted to make sure 89 octane on it's own, or mixed with 87 would be okay. I've heard in the past that it's detrimental to put 93 octane in a car that calls for 87. Thanks for any well-informed help. I'm sure I'll usually put 87, but there is a gas station by me that has 89.
No issue with mixing and u can run 87, 89, 93 octane etc
 
1 - 8 of 8 Posts
Top