Ole Spiff

After reading the many posts about using 87 octane gas, I decided to try a tankful. I just crossed the 5,000 mile mark on the odo and I am rather amazed at the results I got.

When I first bought it, it had a tank of regular from the dealer and performance was "okay"; when I switched to premium there was a noticable improvment so I continued to use premium. Especially since it said it was "recommended" in the manual.

But all the posts on the forum got me to thinking....so I tried a tank of regular. All I can say is I'm amazed. I noticed within about 20 minutes of driving that the engine seemed more responsive; it "leaps" quicker when I touch the gas pedal. Starting from a stop seems a bit smoother. My idle was okay before so I don't notice any difference there. It seems to have as much power as before, just a bit more responsive; it has "sparkle" now when you push the gas pedal.

All this is good, however the real surprise is in the mileage....it is quite a bit better than when I was using premium! In fact, I'm not sure what my mileage is because I'm still running on the SAME tank of regular gas I put in on Thursday of last week (the 16th). It is now Tuesday the 21st! I've done all the same driving to work and back etc. that I normally do; drive it as usual (I don't baby it; I like to put my foot in it) and I still have about an eighth of a tank left. I used to gas up every third day so this is amazing! I work retail so Tues/Wed are my days off. I've driven to work and back for the last 5 days as usual on one tank of gas!

I checked my receipt and I gassed up Thursday morning on my way to work (used Shell regular). I've been thinking about this and I think that not only is the mileage better with regular, but I may be pushing down less on the throttle because the performance is better. Which of course would help use less gas. I normally push pretty far to get that "punch" of acceleration. Since I'm driving by "feel" I must be pushing less because the engine response gives me that "punch" immediately now. Only things I can think of that would explain such a dramatic improvement. Now all this is on a well-broken in engine (over 4K miles); when it was breaking-in, it definitely ran better on premium gas.

Any of you who have at least 3k or more miles on your car I recommend trying a tank of regular if you haven't already; I'd be very interested to see if anyone else is getting these kinds of results.

I have a blue 8 with 6sp MT and I'm in SoCal; don't know if altitude/weather/temps would have that much affect.

Ole Spiff

djmano

titanium grey 6spd in socal here....ive only filled up twice after the gas given to me by the dealer, but ive put in 87 octane both times. im going to try using 87 all throughout break-in, and then see how my car runs. after break-in i will record an acturate MPG and try to take my car to the dyno to see if we can't break 190 rwhp stock

mikeb

there is tons of threads on this check tech threads

Tamas

iTrader: (1)

It's got to be the color... it is a known fact that blue RX-8s are responding very well to the regular fuel whereas all the other colors are not. :D
(j/k of course)

A bit more on a serious note: it's really great hearing the good experiences of people with the regular gas - this is encouraging especially knowing the RX-8's gas guzzling nature (no matter how we look at it, the 8 IS a gas hog). The little difference in the price will be noticeable over time.

Twin 8s!

We have been running 93 Octane because 91 was so hard to find. Based on this thread, I put 89 Octane in my wife's RX-8 to see if there were any differences in performance. First, we live at sea level, (Tampa FL), the temp was 84 today and a little humid. I put 14.2 gallons in so any remaining 93 Octane gas was significantly deluted.

I ran it on the interstate first and noted a some sluggishness for the first 5 miles or so.... or so I thought. After that, it seemed to run very will. I especially noticed good acelleration in 2nd and 3rd up through 6500RPM. I also jumped on it and hit 100 in 5th.

At present we have 80 miles on the tank and I got 68 out of the first quarter tank based on the guage. In comparing this to my RX-8, it seems to be getting as good or better gas mileage.

I will post data when we fill up. I know that some are using 87 Octane, I just thought it would be a less risky approach.

Lastly, please note that I am doing this to my wife's 8 so I cannot keep exact data on mileage cause she drives completely different from me. She runs in 3rd and 4th much longer than I do.


Dave

Sin

Intresting

Ole Spiff

Good to hear I'm not the only one who had this experience. I'm always afraid that I might 'want' the results so it could partly be my imagination, but there's no question about the mileage improvement. I've been running 87 octane for almost a month now and the car runs great. Mileage is staying in the 19's which is better than I was getting with 91 octane. And I'm saving 18 cents a gallon too which adds up.

Now that the temps in Southern California have cooled off and I'm not running the A/C all the time, I hope to get even better mileage.

Ole Spiff

U. N. O.

used 87 2 times in the past.. it gave me knocking noises in 2 and 3 gears after passing 5k rpm. never used it again after that.. be careful.. 87 is no good, 89, 91, 93+ is ok..

i did a thread extensively in this issue do a search

islandsoon

Titaniums seem to run fine on 87...

starstar5

Where would you find 93? All the gas stations where I live (I travel Northern and Southern California), they all have 87-Regular, 89-Premium and 91-Supreme (Names from Chevron). Where would I find a 93?

I use 91 Octane from Chevron since it is recommended by Mazda with Chevron's Techron stuff in the fuel.

Can someone also give us a little more in-dept in the octane rating and what they really mean?

Astor

I know that 93 is available all throughout the southeast, must be some type of nascar carry over. Octane has to do with the rate the fuel combusts, the higher the octane the less likely it is to prematurely combust. I'm sure someone else could offer a more in depth definition.

Twin 8s!

89 OCTANE Update

No loss in performance... just when past 160 miles on first half of the tank. This is about 10-20 miles more than we normally get on the first half of the tank. If this continues, I expect to pull approximately 300 on this tank. From half to on quarter seems to last a while and then it drops like a rock the last quarter.

Ole Spiff

What brand of gas did you use U.N.O.? I found it DOES make a difference. I've been getting the best results with Shell 87 regular which is all I use now.

How many miles did you have on the car when you tried regular? My car had almost 4,000 miles on 91 octane before I tried a tank of 87. It "broke-in" on premium so maybe that made a difference. Mine is running beautifully on Shell 87 octane and has been for weeks.

I live in SoCal though so maybe there's a difference between California gas and other states. We do have stricter emissions standards here so maybe that affects the gas blends too.

Ole Spiff

RX-GR8

i got my best non-highway mileage with Mobil 93 octane. i usually use amoco so i may have to try Mobil some more to see if it makes a difference.

sup3rbad

i haven't seen any 93+ in cali, but when i went to NY and NJ their octane ratings were 89 91 and 93. unlike us in cali with goes 87 89 and 91. did i mention gas was a lot cheaper over there...

Twin 8s!

Useful information related to Octane.

Octane calculation: I found this site which describes how Octane values in the USA are calculated. http://www.csgnetwork.com/octaneratecalc.html

Another thread on Octane stated that other countries had higher octane gasoline that the USA. Based on the data posted there, there is little difference in the quality of gas sold here or abroad. We just average to different Octane values.

Californica gas: The following site describes the differences in the gas sold in CA and the rest of the country. http://www.energy.ca.gov/gasoline/ty..._gasoline.html

JoeRX8ter

Won't be cheaper for long. They are going to add a 15 cent/gallon tax in NJ

tommy12g

I live in miami, fla and all i use is 93 octane, dont want to mess with a good thing

starstar5

That is some really good stat. Where are you from, and what is your car, I mean, which configuration is your 8, and what kind of road condition do you have?

On local commute, my gas reaches middle at around 100-110 miles, if not less. I am strictly using Chevron 91. Well, though this time I fell short and had to use a no-brand 91 (on military base). It seems even less mpg for me, but we will see.

Twin 8s!

We live near Tampa Fl. We have two RX-8s.... hence the username :D .... Both 6MT. Basic models with no frills... bought them to drive... not goof with a nav system.... (personal prefrence... no slame on those who want more widgets)

I am going to continue to track the mileage differences between 89 and 93 Octane. It is just a pain the #$$ to find stations with 91 here. For whatever reason, I can only find it at Citgo stations with newer pumps. We are running Raceway gas which comes from who knows where but but cars seem to run well on it.

Lastly, I think it would be interesting to build a matrix listing mileage by state/region and octane used. I have been doing some reading, and I wander if the "reformulated" gas sold in CA and a section of the northeast may be the problem. Also those using corn gas may want to provide data. Just a thought.