Nd4SpdSe

Australia & Europe: RON - Research Octane Number:
The most common type of octane rating worldwide is the Research Octane Number (RON). RON is determined by running the fuel in a test engine with a variable compression ratio under controlled conditions, and comparing the results with those for mixtures of iso-octane and n-heptane.

Canada & USA: AKI (RON+MON)/2
In most countries, including all of those of Australia and Europe the "headline" octane rating shown on the pump is the RON, but in Canada, the United States and some other countries, like Brazil, the headline number is the average of the RON and the MON, called the Anti-Knock Index (AKI, and often written on pumps as (R+M)/2). It may also sometimes be called the Road Octane Number (RdON), Pump Octane Number (PON), or (R+M)/2.

Motor Octane Number (MON), or the aviation lean octane rating, which is a better measure of how the fuel behaves when under load, as it is determined at 900 rpm engine speed, instead of the 600 rpm for RON.[2][3] MON testing uses a similar test engine to that used in RON testing, but with a preheated fuel mixture, higher engine speed, and variable ignition timing to further stress the fuel's knock resistance. Depending on the composition of the fuel, the MON of a modern gasoline will be about 8 to 10 points lower than the RON. Normally, fuel specifications require both a minimum RON and a minimum MON.

http://en.wikipedia.org/wiki/Octane_rating

Chad D.

iTrader: (19)

Per volume, yes, you will have a lower alcohol content.

My snowmobile is a 303 sachs wankel.

Mazda_RX804

Ultra 94 FTW

FastFreddy61

I guess I'll stop drinking. Chad, are we in agreement yet .? Nd4, thank you for the explanation.

terch1

iTrader: (2)

Dude if you can't afford the couple extra dollars to fill your tank with premium your probably driving the wrong car. All I can say is wow there are some real cheap asses out there.

Chad D.

iTrader: (19)

I use 91/

schnipster

all of this premium gas in my opinion is nonsense, there isnt a car on the road that cant run on 87, as usual rx8 owners(god bless them) love to make thier cars sound like its an old vintage bottle of wine.......the only reason you need to use premium is because when the ****** at mazda have to replace your engine they are going to sift through your **** to find a loophole that will allow them to tell you to go take a hike....not using the gas that it says to use is a one way ticket to them saying you are out of luck...jokes

PS my fathers twin turbo 911 will rip your butthole out of your *** running on chicken soup.....i have done it...87 octane with no issue......

xun4gvn4everx

iTrader: (2)

You go ahead and run your 8 on 87. I'll see you in the new engine thread with your explanation to mazda

terch1

iTrader: (2)

Pony up and buy premium people.

schnipster

i just have not seen proof that it actually matters...i have seen high compression, turbo, supercharged engines run low octane with no issues...the only cars i have seen that really get bratty with lower octane fuel have all had a latop on the passenger seat...cars that are nowhere near showroom stock...just my observation...

schnipster

and for the record i only run 91 or higher...but i only do it so the mazda demons cannot say a thing when this baby blows up.

alnielsen

iTrader: (4)

I used to race the RX7's on 87. It made more power.

schnipster

made more power..can you expand on that a bit.

alnielsen

iTrader: (4)

I went faster. Was at a higher RPM entering a corner.

fevest

As for mazda dumping your warranty for running 87, unless you tell them I doubt they will know. My dealer doesn't have the equipment to test the octane level of the fuel in the tank.

terch1

iTrader: (2)

^ +1 Although the dealership can't test the octane of fuel in your tank I run the high octane anyways. I do this for the same reason I use 5w 20 oil and that is it is whats recommended in the owners manual.

alnielsen

iTrader: (4)

The key word there is "recommend" and not required. If a fuel doesn't meet the engines requirements, the PCM will make the necessary changes.

schnipster

the same r&d team that determined the octane level required for this motor to operate properly has all thier findings and testing documented....when they ran low octane the results were documented...if your motor has the same symptoms...they will for sure at minimum accuse you of not using the proper fuel...addding miles and limes of red tape to an already painful process.

schnipster

same with the oil...bet your *** that using the reccommended oil is a great idea...

oltmann

I believe it. I also believe that CSI is a documentary.

schnipster

it isnt?

oltmann

Exactly.

wankelbolt

iTrader: (21)

What you are forgetting is that the EPA requirements override sound engineering principles. Mazda engineers sure as hell wouldn't have specified 5W20 if it wasn't for the EPA. It is barely adequate for the job of lubricating your engine. And inadequate for the long-term. Search around for tear-down threads and see for yourself.

So don't think that "cuz the manual says so!" means that it's the right choice. Nor that using something other than what the manual says will automatically void your warranty. It will not. The burden remains on the mfg to prove the change caused the failure.

maitre

iTrader: (1)

So where do you go for your unbiased opinions on this matter? Do we have a field expert we can defer to? Or are we treating long-term rotary owners as the "experts" here?

To answer the opening question, "will it harm the engine"? The answer appears to be that no, it will not. Will it put "extra wear" on the engine? That is debatable, but so will your driving habits (i.e. mashing the gas with 87 in the tank, good idea? Maybe not.)

If you want to experiment, be prepared for mixed results. If you *don't* want to experiment, you better stick to the recommended specs, and buy 91.