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hi - the honda press kit says the 2017 sport touring hatchback "is designed to benefit from" premium 91 octane........is that primarily for higher level performance? if you run it on 87 octane, would it run poorly? reduced mpg? long-term engine problems? i've spoken with some sales guys, some honda shop mechanics, some confusing info.......thx for any input
I though it would be better to resurrect this thread, rather than posting a new one. I have a 2020 Sport Touring. The manual (page 558, see attachment) states that "Unleaded premium gasoline, pump octane number 91 or higher" gas is "recommended" (not required, per se,) for models "...with 18 or 20 inch wheels" (page 24) My car does have 18 inch wheels, and I have been using the 87 octane.
The manual goes on to say:
"Use of a lower octane gasoline can cause occasional metallic knocking noise in the engine and will result in decreased engine performance.
Use of a gasoline with a pump octane less than 87 can lead to engine damage.The use of regular unleaded petrol can cause metallic knocking noises in the engine
and will result in decreased engine performance."
Has anyone used 91 octane in the Civic, and noticed a difference in performance and/or gas mileage? I have a lead foot at times, so I may experiment with 91 octane.
Last edited by SaxTouring; 06-17-2020 at 11:00 AM.
I though it would be better to resurrect this thread, rather than posting a new one. I have a 2020 Sport Touring. The manual (page 558, see attachment) states that "Unleaded premium gasoline, pump octane number 91 or higher" gas is "recommended" (not required, per se,) for models "...with 18 or 20 inch wheels" (page 24) My car does have 18 inch wheels, and I have been using the 87 octane.
The manual goes on to say:
Has anyone used 91 octane in the Civic, and noticed a difference in performance and/or gas mileage? I have a lead foot at times, so I may experiment with 91 octane.
I have a 2018 Sport Hatchback and I did an experiment on a long road trip with both 87 octane and 91 octane. Road and atmospheric conditions were fairly consistent on this road trip, and I did one tank on 87, and followed up with a tank of 91. I did a gradual acceleration to 83 mph (to not affect average fuel economy too much), then set the cruise control to 83mph for both tanks. Here's what I observed:
87 octane tank:
Average fuel economy meter stuck at around 32mpg
Acceleration to 83mph was very slow and gradual
91 octane tank:
Average fuel economy meter stayed above 36mpg, often sitting in the 38-42 range
Acceleration to 83mph felt a lot easier for the car to accomplish with the same throttle input.
I actually had more fuel in the tank than I had expected, so my final average fuel economy for that tank took a steep dive because I was able to drive around San Francisco for the remainder of that week visit without having to refuel (until I prepped to leave back to Vegas)
Needless to say, that was enough for me to fill up with nothing but 91 octane. That, and I have a KTuner 21psi tune, and that requires 91 octane.
With regards to "recommending" 91 octane in the Sport and Sport touring models with the 1.5T, it has a different knock sensor (and thus ECU programming) than non-Sport models. Lower octane will cause more engine knock, and the car will retard timing a bit to pull a bit of power to protect the engine. My understanding of how the Sport/Sport Touring gets that 6hp bump from the EX trim *when using 91+ octane, at least. It's also quite consistent with the manual, as it states "more knock... decreased performance.." with regards to the 18/20" rim models (Sport/Sport Touring/Si/Type R all come with 18's or 20's from the factory)
Last edited by xRiCeBoYx; 06-18-2020 at 03:28 PM.
Reason: Edit for clarity
Thank you for both for your input. The strange thing is that Honda is recommending either 87 or 91 octane gasoline for the same engine, depending on what size tires are being used. The manual specifically states that knocking and engine damage should not occur as ling as a minimum of 87 octane (e.g. regular unleaded) is used in the vehicle, regardless how large the wheels are. So, the only remaining question is whether or not the use of premium gas is enough to justify an extra $7 per tank.
it's less of the wheels being used, but more of what trim levels come with those wheel sizes. Sport/Sport touring/Si have a slightly modified L15B7 1.5T and come with 18s. The EX turbo has the "standard" L15B7 1.5T and comes with 17's. Type R has the 2.0L turbo and comes with 20s
it's less of the wheels being used, but more of what trim levels come with those wheel sizes. Sport/Sport touring/Si have a slightly modified L15B7 1.5T and come with 18s. The EX turbo has the "standard" L15B7 1.5T and comes with 17's. Type R has the 2.0L turbo and comes with 20s
Originally Posted by BrotatoChip
I agree it is odd to specify based on tire size as opposed to using the trim level. I'm sure they had a reason for it but I cannot figure it out.
xRiCeBoYx's response makes sense. It sounds like the trims that have 18" or 20" wheels have a slightly different engine, which can benefit from an octane boost. That said, it seems that the engine should run fine with 87 octane, with no risk of knocking. I'll try premium gas in mine at some point, to see if I can notice a difference.
03-15-2017
