Octane and mileage

I'm seriously considering buying an RSX Type-S and would like to know a couple of things from people who own one, or have owned one. I read somewhere that Acura recommends high octane fuel (91 if I remember
correctly) be used for the Type-S model. My question is What happens if regular (87) octane is used instead? Can it cause any damage to the engine? Will it reduce the gas mileage, and by how much? The second question is what mileage per gallon are people actually getting with this car? The sticker shows 23 City / 31 Highway, but my experience with the 1990 Honda CRX Si that I used to own proved that actual mileage can vary quite a bit from what is reported on the sticker. I consistently got between 36 and 40 mpg with my CRX, depending on the ratio of city to highway miles, but the sticker said 28 City / 33 Highway.
Thanks, Joe
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We leased a 2006 RSX-S one month ago. The car has 900 miles or three tank fulls. So far the mileage has been 26, 28 and 29 mpg. The last on regular fuel with no noticeable difference in performance.
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Thanks for the info. It looks like your mileage is improving as your engine breaks-in. It's promising to hear that you were able to use regular octane gas with no discernable problems. Although the guy who replied right after you paints a bleak picture of doing that.

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The question of using regular 87 octane fuel in Honda cars that are placarded as requiring premium (91 or higher octane) has been discussed many times in this group.
Honda (Acura) firmly recommends premium only except in cases of emergency, when regular can be used for a short period to get to a gas station and a fill up with premium. The car must be driven "gently" to reduce risk of detonation onset while regular is being used.
The issue here is compression ratio's and the very real risk of detonation if a high compression ratio engine runs on a fuel with too low an octane rating. There is no guarantee that detonation sensors (sometimes called "knock sensors") will catch detonation and retard fuel amounts and timing fast enough to save an engine when detonation occurs. Detonation can destroy pistons, rings, valves, connecting rods and rod bearings, basically trashing the engine and this damage can occur in fractions of a second.
The cost of an engine replacement or rebuild would far exceed the small additional cost of premium fuel over the life of the vehicle.
Finally, it would make no sense to put a fuel in a performance oriented car which would then require you to drive it extremely gently and at risk of blowing the engine at any moment.
I'll leave it to others to address the fuel mileage issue.
Paul
On Sun, 18 Jun 2006 22:14:50 -0700, Joe McArthur

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if thats the case why does the manual say only that lower octane can be used with reduced performance...nothing else is mentioned?
And if you are too cheap to get 91 octance fuel, just get the base RSX...
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On Mon, 19 Jun 2006 19:34:54 GMT, James said:

Or get a Corolla.
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Most Hondas are designed for 87 pump octane. The ones that are not have very high compression ratios. Does YOUR car require 91 AKI? Look up your Owner's Manual from Honda, here: https://techinfo.honda.com/rjanisis/logon.asp (You do not need to log in to access the Owner's Manuals, and there are a few '07s available now).
The easiest way to find things in your Owner's Manual is to ignore the Table of Contents and go straight to the Index at the back.
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wrote:

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Correct.
87 is OK for other models. The Type-S MUST use 91.
All other models have a compression ratio of 9.8:1, which is already pretty high, but the Type-S has a whopping 11:1 ratio! ELEVEN to one, people! There was a time you never saw such a thing off the racetrack.

According to the Owner's Manual, it can cause pinging and possible engine damage.

Yes, if you run into a bad batch that tests below 87.

Nobody knows. I suspect mileage loss would be slight.
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Is the performance advantage over the base model worth the additional expense, both up front and at the pump? Tough question, one I pondered for quite a while. My decision was helped by running into a low mileage base model at carmax, at a very low price. I had test driven a type s, and was almost ready to go with it, but test driving the base model pointed out something you can see in the specs, but might avoid seeing if you've got type-s lust - in normal day-to-day driving on normal city roads, there's virtually no difference in the performance.
Two other disadvantages of the type-s that're not immediately obvious - the low frequencies from the exhaust make a significant difference in cabin noise, and will cut your bass frequencies in your stereo. And the stereo in the type-s is much harder to upgrade - if you actually like the stock stereo, fine, but most music heads don't.
Mileage - my experience with my base model is that it's right exactly what the sticker says, not significantly less, and certainly not any better.
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Thanks a lot for your post. It was very helpful to my decision making process. I'm definitely going to take a closer look at the base model.

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We were sold on the S because of the attractive lease options offered and the resale value of the S type. The car is very desirable by a younger market segment. It should be within their price range after three years. When the lease expires there is a buyout option and the possibility of selling it at a higher price than that option. Or we could keep it! ;>)
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The Type S is not worth it for most drivers. Through first and second, a base holds up pretty well in a race against a type S. Once you hit 3rd gear the S will start to pull. But if your not going to the track to race, and hopefully not street racing, you won't notice much of a difference. I think stock, the Type S is 1 second faster then the base. An entire second...wow. To the average driver, who cars. Are you the average driver?
Or you could buy a base, and add a CAI, header, exhaust, etc, and come out as fast as a Type S, have some extra money in your pocket, and save on gas.... Also the Type S burns oil, and has some tranny problems that don't seem to effect the base

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Here is my gasoline record. My type S has yet to burn oil or have any other problems. I love the car. 2005 Acura RSX type S Odom Miles Gal MPG Cost C/ Gal 05/14/05 11 05/18/05 175 164 5.688 28.8 $13.19 $2.319 FastPay, Penrose 05/31/05 9.217 33.5 $20.21 $2.300 Mills River Gashouse 06/13/05 7.348 33.5 $16.90 $2.290 Etowah Quality Plus 06/15/05 7.237 33.5 $16.78 $2.300 Citgo 06/18/05 11.190 33.5 $25.74 $2.299 Whalebone 06/18/05 1664 1498 9.653 33.6 $22.58 $2.339 Shell 06/27/05 1975 311 10.213 30.5 $23.28 $2.279 Etowah Quality Plus 07/19/05 2257 282 10.287 27.4 $25.71 $2.499 Quick Mart #2, Horseshoe 07/31/05 2581 324 11.107 29.2 $27.09 $2.439 Enmark, Hendersonville 08/25/05 2840 259 9.142 28.3 $25.13 $2.749 Mills River Gashouse 09/15/05 3131 291 9.757 29.8 $29.65 $3.039 Etowah Quality Plus 09/21/05 3410 279 8.959 31.1 $25.52 $2.849 Etowah Quality Plus 10/06/05 3722 312 10.060 31.0 $34.06 $3.386 Etowah Chevron 10/14/05 4013 291 9.910 29.4 $28.33 $2.859 Mills River Gashouse 10/22/05 4170 157 5.577 28.2 $15.72 $2.819 Etowah Quality Plus 10/31/05 4470 300 9.691 31.0 $26.16 $2.699 Quick Mart #2, Horseshoe 11/10/05 4782 312 10.566 29.5 $25.98 $2.459 Etowah Quality Plus 11/23/05 5059 277 9.200 30.1 $20.97 $2.279 Mills River Gashouse 12/14/05 5327 268 9.917 27.0 $23.79 $2.399 Quick Mart #2, Horseshoe 12/23/05 5599 272 9.687 28.1 $23.24 $2.399 Quick Mart #2, Horseshoe 12/30/05 5852 253 9.283 27.3 $21.43 $2.309 Etowah Quality Plus 01/06/06 6139 287 9.280 30.9 $22.27 $2.400 Amaco 01/08/06 6432 293 9.708 30.2 $22.32 $2.299 Union 76 01/11/06 6685 253 8.900 28.4 $23.70 $2.663 Chevron, Mars Hill. 01/21/06 6958 273 9.296 29.4 $22.77 $2.449 Mills River Gashouse 01/28/06 7253 295 10.025 29.4 $24.55 $2.449 Etowah Quality Plus 02/10/06 7524 271 9.838 27.5 $23.99 $2.439 Mills River Gashouse 02/22/06 7808 284 10.361 27.4 $24.34 $2.349 Etowah Quality Plus 03/03/06 8057 249 8.743 28.5 $20.88 $2.388 Etowah Quality Plus 03/05/06 8377 320 10.812 29.6 $26.00 $2.405 BP S Carolina 03/10/06 8674 297 9.780 30.4 $23.46 $2.399 Shell S Carolina 03/12/06 8906 232 7.594 30.6 $18.45 $2.430 Ingles, Fletcher 03/21/06 9183 277 10.162 27.3 $27.33 $2.689 Enegry Mart #3 04/04/06 9475 292 10.594 27.6 $30.29 $2.859 Quick Mart #2, Horseshoe 04/09/06 9748 273 8.827 30.9 $23.47 $2.659 Ingles# 53 04/22/06 9967 219 7.422 29.5 $22.41 $3.019 Etowah Quality Plus 05/03/06 10253 286 9.684 29.5 $28.65 $2.958 Etowah Quality Plus 05/15/06 10595 342 11.084 30.9 $31.91 $2.879 Etowah Quality Plus 05/26/06 10924 329 10.762 30.6 $31.52 $2.929 Quick Mart #2, Horseshoe 06/01/06 11198 274 9.343 29.3 $26.24 $2.809 Etowah Quality Plus 06/02/06 11532 334 10.034 33.3 $29.59 $2.949 Nashville, Tn 06/03/06 11877 345 10.471 32.9 $30.25 $2.889 06/03/06 12127 250 8.027 31.1 $22.31 $2.779 Ok 06/03/06 12472 345 11.220 30.7 $32.41 $2.889 Amarillo, Tx 06/04/06 12660 188 5.931 31.7 $18.74 $3.160 06/04/06 12920 260 7.956 32.7 $26.25 $3.299 Gallup, NM. 06/06/06 13221 301 8.844 34.0 $28.82 $3.259 Prescott, Az 06/08/06 13519 298 9.225 32.3 $32.09 $3.479 Mecca, Ca 06/10/06 13828 309 11.013 28.1 $37.87 $3.439 San Diego, Ca. 06/13/06 14091 263 9.822 26.8 $34.96 $3.559 Banning, Ca 06/16/06 14413 322 10.374 31.0 $36.92 $3.559 Porterville, Ca. 06/19/06 14694 281 10.265 27.4 $35.71 $3.479 Lancaster, Ca 06/21/06 14925 231 8.510 27.1 $29.95 $3.519 Palm Desert, Ca. 06/22/06 15255 330 11.257 29.3 $33.42 $2.969 Az 06/23/06 15482 227 7.786 29.2 $24.00 $3.082 Cash 06/23/06 15770 288 9.298 31.0 $29.28 $3.149 Van Horne, Tx. 06/23/06 16067 297 9.443 31.5 $28.32 $2.999 Sweetwater, Tx. 06/24/06 16346 279 8.642 32.3 $25.05 $2.899 Terrell, Tx. 06/24/06 16707 361 11.395 31.7 $32.46 $2.849 Clinton, Ms. 06/25/06 17023 316 10.040 31.5 $29.11 $2.899

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Looks like you're getting pretty reasonable mileage there. What octane rating have you been using? A salesman at my Acura dealership was pretty convincing when he told me that he never puts anything higher than 89 octane in his Acura TL (not sure if that was the exact model or not) and never experiences any engine knocking or other problems. He says his model has the same "recommendation" of 91 or higher, as the RSX Type-S.
While I was at the dealership I test drove the base model, hoping I wouldn't notice that much of a difference from the S-type, so as to convince myself that I'd be happy with it. But unfortunately that was not to be. I felt that the performance of the Type-S I had driven before was significantly better and knew that if I bought the base model I'd always be wishing I'd have gotten the S-Type instead. So I ended up buying a Type-S. I'm pretty happy with my decision and hope that the car will be happy with 89 octane (haven't had to fill the tank yet). :)

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I use premium like the mfg recommends as the compression ratio is 11 to 1. I have not tried the lower octants.

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I've got a base model and LOVE it.
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"Joe McArthur" < snipped-for-privacy@vfemail.spamblock.net> wrote in message
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