I've been having warm/cold start problems with my car. Even though I've never put anything but Shell V-Power (93) in my car, when I spoke to a Mazda tech, the first thing they asked me was if I used premium gasoline because I was told the higher octane grade allows the car to run better at warmer temperatures, which the Rx8 naturally runs hot and with the 10% ethanol that is in all gas now, that is already is hurting the Rx-8, so using a lower grade of gas will severely decrease performance and make the engine run at a way higher temperature which causes the apex seals to go bad. (They didn't ask about oil because I service my car at their dealership every 2,500 miles and sometimes buy oil from them from when I need to add oil to top it off)

Honestly, just do what is recommended, it's about .10 less than the 91-93 so you're honestly going to save about $1.30-$1.40 at most and the Rx-8 already gets horrible gas mileage, so even if it increases by 1-2 mpg (which mpg always varies on temperature, etc) you're not going to save much. If you got an extra mpg, you're going to save at the most 14 miles, which is barely $2-3, and a new engine is roughly $3,000 (if out of warranty) and they can tell somehow on the fuel you're using, I'm not sure how but that is what I was told from the dealership & other Rx-8 owners who have had low compression engines.
If you can't afford to pay at max a $3-4 difference at the pump, sell your Rx-8 because you should be driving a Honda Civic. Or check your coils, plugs, wires, etc. Before I changed mine, I was getting horrible gas mileage, after the change it really helped. (Every 20k, it really makes a difference)

Also, my neighbor has an Rx-8, and he gets roughly 13 mpg in the city and I asked him if he's used premium gas or if he's ever used any brand of Premix, such as Idemitsu Racing Premix, he said no and that he uses 87-89 and he's much older guy than me so I'm guessing he babies it and he doesn't play fast and the furious at stop lights. I get about 18 mpg in the city using (93). I don't even think you get a better mpg using 89, it doesn't make sense.

 

Thankfully, I'm blessed with a Series II, so my engine is a bit less fragile than yours. That said, I generally run 93 Shell V-Power as much as I can, but lately I've been a little crunched on cash with my job cutting back hours. $4 dollars can buy a decent meal.

 

I understand you have a series II, but the only difference between the series I and series II engines is the third oil injector. Sorry to hear about your job though.
Trust me, I know where your coming from, I'm a guitar instructor at a music school that's about 20 miles from my house and because of the economy the demand for lessons is not a priority right now. If the $4 is going to make or break you, you should try to find out if you can car-pool with anyone that lives close to you and goes to the same workplace (or near-by.)

 

plus the difference for us here is roughly .10 per liter so for a full tank its about 6 bucks difference, ends up being 25 a month and not as often to fill up. llike polish person said ( im polish aswell lol ) it adds up and the difference in horsepower is not that much of an issue, once i turbo my car ( when the warranty ends ) I will start using premium again.

 

Right here in Las Vegas, gas is going up and up and i just filled up my RX8 yesterday roughly almost $60! Last 2 weeks ago, it's $50!

Here we go again... gas is spiking again! I use 89 octane all the time, Chevron gas only

 

87. Engine doesn't ping on that, and I've read the good threads on this topic.

 

See 80 would be lowest I go, 87 to me sounds scary, so you experience loss of power, how does that affect your mileage?

 

I filled up today... 82€
However a datalog should tell something about what you're putting in and how it behaves if you have a comparison with another fuel.

 

^ I always put 89 octane, Chevron gas only. That's how i am.

I'm not picky or anything, it's just the way i got used to... i guess.

 

so you like doing things not the way they are supposed to be?
1. Cutting springs to lower the car
2. Putting 89 gas when the car is asking 91+

what can I say, lol.

 

There is no loss of power, nor any change in mileage. The engine doesn't retard timing, because it doesn't knock. See how that works?

 

It's called "modifying".

meaning: changing or adjusting an original parts (the right way)

 

or you know you could be a bit "cheap"?
its like asking your mom for a strip dance because shes a woman and free.

 

Omg! ^

 

 

I'm a student, and apparently the only one that doesn't live on campus. Haha. It's hard to sync schedules with people. But the semesters started already, so I don't have to buy books/softward/random-**** anymore. Instead, TEIN coilovers ASAP!

Native born? I am. It's a pleasantly grey country. TURBO FTMFW! If Mazdaspeed released some sort of FI kit for the SII RX-8 (since it's mildly more reliable and still for sale) with a limited warranty, it would make the RX-8 viable for another 2-3 years.

 

Yeah moved to canada when I was 4, 22 years ago

 

This is kind of true but don't ever trust our knock sensor. It's not the most reliable item in the world and actually starts working when it is too late usually!

So I assume you don't modify your cars but goof them up instead?

 

I will rephrase; the engine doesn't retard timing. So, by what mechanism do people think mileage/power will go down on lower octane?

 

tanks is at the quarter now and i'm at 235km

 

pretty sure it retards timing. thats what the knock sensor for.

 

*pulls 'chute*

 

okay did 263km, put in 47L gave me 17mpg. so honestly not much better by roughly 3 mpg, but i think my coils are due and so are my plugs.

 

Originally Posted by bse50

So I assume you don't modify your cars but goof them up instead?


^ The old fashion way...

If it's been done before, it could be done again

 

My uncle ran away from Poland to Canada a long while ago. Now he works pretty high-up at Phillips Morris and is doing quite well. Anyway, seems a lot of Polish people move to Canada.