I'm running Chevron 94 octane here, and i'm averaging about 310-330km per tank about 50/50 hwy city driving... I see some people are using 87 octane???! Can you do that? Also I tried Mohawk gas in my car 92 octane which contains up to 10% ethanol... I got 290km to the tank and the car was slugging around... Anyone have similar problems?

 

I 've been using 87octane 10% ethanol since the car was new. After 26k miles I have had no problems. I tried 93 octane 10% ethanol a few times. Performance was a little crisper but then became unnoticeable on the second tank. Gas mileage seems about the same for either octane but I never really checked calculated the miles /tank. I get about 18-20 mpg combined avg.

PS. you'll get worse mpg with entanol blends regardless of the octane.

 

93 is best we have around here in michigan that I have found. I get about 280mp/tank (roughly 18mpg) with about 50/50 hwy/cty).

 

93 or nothing can notice a difference in performance over 87 and it just doesn't run right on hot days here in pa but now it's away for the winter so i buy 87 for my winter beater.......figure 20 cents a gallon more thats like 2 or 3 bucks a tank more and u get better performance.....i'd use the 94 like u r now

 

I generally run 89 octane "premium" fuel. Whenever I get a gas card or around once a month or so, I'll fill up with 91 "super"

I don't really notice a difference between the two. I'm more concerned about preventing engine knock then max HP.

I try to avoid ethanol as it is more environmentally/sociologically unsound then gasoline can ever dream of, and it eats aluminum (though I have no proof whatsoever that 10% is going to harm your engine, nor do I suspect it will.)

 

The owner's manual recommends 91 for best performance, but says you can use as low as 87 with slightly reduced performance. There are a lot posts here reporting different results for various grades. The best grade to use seems to be an individual thing - not as deterministic as with piston engine cars.

Ken

 

I think high octane works best for small high performance engines in hot weather. Otherwise 87 octane should do. The manual does not mandate 91 octane.

 

actually it does... page 81 of the manuel (fuel requirements)

Fuel Octane Rating* (Anti-knock index)
Premium unleaded fuel 91 [ (R+M)/2 method] or above (96 RON or above)

http://www.analogstereo.com/pdf/om/m...anual_2004.pdf 2004s

http://www.analogstereo.com/pdf/om/m...anual_2005.pdf page 87 on 2005s

http://www.analogstereo.com/pdf/om/m...anual_2006.pdf page 117 on 2006s

http://www.analogstereo.com/pdf/om/m...anual_2007.pdf page 123 on 2007s

 

I was running 93 and put in some 89 and it started running like crap, the idle was more rough and stuff.

 

It doesn't mandate that. Just says the car will run best with that. The only things it mandates are lead free, no more than 10% ethanol, and octane at least 87.

Despite the lack of mandate, I still run Zoomy only on 91 or better.

Ken

 

Go down a few sentances, it explains 87 octane (91 RON). Correct me if I'm wrong but 91 Ron must be 87 octane. No pinging on my car with the 87 octane gas so I use it..

 

why do they even make owners manuals for these cars, no one ever uses them and if they do they still deviat from what it says!

 

On my reman motor (2k miles), I originally used 93, then switched to 89 after 1k and have noticed no difference.

 

So those of us who read the manual and those of us who don't have another thing to argue about.

Ken

 

haha

 

If using 93 octane breaks your budget, you're in trouble.

 

yaaa when I ran 92 octane mohawk gas with the 10% ethenol... when I would engage the clutch the car would almost shudder when I engaged it into gear everytime... it was just running to rough... so with my last tank I put in 94 chevron
and instantly after I started it up and was pulling out of the parking lot it seemed to respond 10x better and seemed much more peppier... maybe its just me?!!! :|

 

I always fill it up with 93, I tried maybe couple of tanks of 87, not continuously tho. It ran like crap, might have something to do with my premix level. I premix like 8-12 oz per tank depends on my mood, and it was a pretty hot day (like 90 degrees?) I can feel that its retarding the timing cuz I cant really push it too fast. As soon as I put 89. its fine.

Well, some people just want to save a few bucks you know. Say if you save 3-4 bux per tank, after 10 or 15 tanks you can have another tank for free(well, the money that you saved). so ... not like people cant afford it, but if its not really needed. why not ?

I've been thinking about going for 89 for the winter, cuz its freezing like **** in NYC this winter. tonight its like what 38 ? Last week I've seen 21. So .... thinking.

but I still wouldnt do 87 tho. consider the premix that Im using.

 

if you can run 87 without problems, run 87. if your car runs poorly with 87 then go for better gas.

 

It's not needed to premix the gas. That's what your oil metering pump is for, it premixes the right gas for you depending on the RPM level. 94 is required for the engine to prevent detonation. If you buy this car, guess what, it sucks the gas. Why even bother to check your fuel efficency, that's not what this car is for.

I'm surprised no one has said "go buy a prius" yet. They usually do.

 

wow,

seems like you are a bit behind the power curve..

87 oct. except for track days
premix yes i do
omp ? life is not always perfect. are you sure how good it is..

~ 21mpg.. my average over 80k miles.

beers

 

From RotaryGod:
"I am not against premixing in any way. Here are my thoughts on it though.

The engine already gets oil injected into the combustion chamber to lubricate it. While you don't want too little oil, you also don't want too much. I definitely agree that 2 cycle oil is the best way to go and that standard motor oils suck in the combustion chamber. However, I am not a fan of using oil injection AND premix. Use one or the other. Unfortunately if you disconnect the omp on the RX-8, the car will drive in limp mode. This isn't good.

The engine has different lubrication requirements based on rpm and load. The omp varies the oil into the engine based on this. Premixing leaves you with one set ratio. Typically it is the maximum amount based on max loads and rpm's. This leaves you with too much oil for 99.9% of your driving. Running a really small amount of 2 cycle oil shouldn't be a problem but it also isn't really necessary.

The best overall option is to install an adapter in between the engine and the omp that will let you pick up oil from an outside reservoir. This way you can run 2 cycle oil through the omp system and have it metered in the correct amounts. The engine oil also isn't circulated and now there is zero reason why you can't run synthetics. This is the best option.

Too much oil will hurt performance in the long run. If you still want to run premix with the factory system hooked up, use a higher ratio such as 600:1 or 800:1. Keep it low though."

Off topic I know, but you shouldn't pre-mix unless you know what you are doing. It's not being behind the power curve, it's having common sense to let the engineering do the work for you instead of reinventing the wheel. The owners manual says to use 94 octang, so that's what you should do. Why risk detonation in your engine? I mean you don't buy a $30,000 car and put cheap gas in it or worry about gas efficiancy when clearly that's not what this car is for.

 

yep,

great stuff in theory. but if you pay attention to how much oil you motor uses it reveals a lot..

you can pay me now or pay me later...

as it seem you have read just the highlights.. i run 5 to 8 oz of premix.. i works well.. you might search for good posts on mop and premix mpg gains...

i will agree for the most part less is more..

but to burst your bubble. mazda has been reflashing for the omp since the car came out.. say hi to my little friend epa.

i think fred might back me up on this... that is rotaygod...

beers

 

To bring this post back on topic, my original point is to just do what the owners manual says to do (unless you have tuned your car) and you'll be fine. People need to quit complaining about the cost of gas and fuel consumption on a car that's clearly not meant to statisfy the Al Gore propaganda cool-aid drinkers. Whatever you want to do with your engine with premixing is fine. But I've never had any problems with my 04 and I'm the orginal owner and I drive the car like it is supposed to be driven AND do what it says to do in the owners manual.

 

87 octane for 3 1/2 years of ownership with no ill effects at all. I've tried 93, 89 and 87 and there is positively no difference in performance, no hint of knock and no change in fuel mileage. I can easily afford the 87, but if there's no difference in performance, why bother with it?