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I have a 2018 mz3 2.5L hatchback.

Do you know if it’s okay to run higher octanes stock without getting a tune or modifications to the car or what he beat octane would be for the engine? The user manual says 87 but not sure if it’s okay to run 91 and 93 safely on just the stock map.
 

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Why? It won't do anything any better than 87 octane gas. The only difference is your wallet will be lighter. My car actually seems to run better on 87 octane anyhow. The best octane is what the manual says to use. I think that the people who actually designed and built the car would know.....:laughing001:
 

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Why? It won't do anything any better than 87 octane gas. The only difference is your wallet will be lighter. My car actually seems to run better on 87 octane anyhow. The best octane is what the manual says to use. I think that the people who actually designed and built the car would know.....<img src="http://mazda3revolution.com/forums/images/smilies/laughing001.gif" border="0" alt="" title="laughing001" class="inlineimg" />

Hey arathol ? Wasn’t sure what was “better” for the engine lol
I was also looking at OVTune and it looked like they had tunes for the different octanes...if I decided to get a tune from them I didn’t want to harm the engine while transitioning to a higher octane ? not quite sure how that works though to be honest...
 

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Hey arathol ? Wasn’t sure what was “better” for the engine lol
I was also looking at OVTune and it looked like they had tunes for the different octanes...if I decided to get a tune from them I didn’t want to harm the engine while transitioning to a higher octane ? not quite sure how that works though to be honest...
If you are going to get a tune decide what one you are going to use, then start filling your tank with the appropriate octane gas well before starting the process to cycle the lower rated gas out. If you do a 93 octane tune with a tank thats half full of 87 you won't get good results. Higher octane won't hurt anything, it just won't help either with a factory tune.
 

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Hoon Apprentice
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Yes, you can run anything above or at 87 octane. Just don't expect any astounding results without a tune. I run 89 in my '16 2.0l but only because the SRI doesn't seem to like regular 87 octane at 95+ degrees F ambient outside temperatures.
 

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it feels so weird to put the cheap gas in my new car.....shudders
 

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The minimum octane rating available in the UK is 95 RON (Research Octane Number). I understand the US uses a different octane standard - the Anti-Knock Index (AKI), and often written on pumps as (R+M)/2. It may also sometimes be called the Posted Octane Number (PON). The UK 95 RON fuel roughly equates to a US rating of 90. We also have super premium petrol with a rating of 98 RON. Many claim this give 10% better fuel economy but I didn't find much difference. My dealer did tell me you need several fuel tank refills for the car to 'learn' the fuel grade. There was no mention of needing to retune the car.
 

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Hoon Apprentice
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The minimum octane rating available in the UK is 95 RON (Research Octane Number). I understand the US uses a different octane standard - the Anti-Knock Index (AKI), and often written on pumps as (R+M)/2. It may also sometimes be called the Posted Octane Number (PON). The UK 95 RON fuel roughly equates to a US rating of 90. We also have super premium petrol with a rating of 98 RON. Many claim this give 10% better fuel economy but I didn't find much difference. My dealer did tell me you need several fuel tank refills for the car to 'learn' the fuel grade. There was no mention of needing to retune the car.
Yeah, within reason, the car can technically "tune" itself for better octane fuel. It takes a few tanks full, and only nets you about 2-5% more torque and [arguably] maybe a mpg or two. However, it is not a true tune, but, rather, that the anti knock sensor backs off of its parameters just a tiny bit because higher octane is less volatile.

the lower the octane fuel, the more the knock sensor slows the ignition of the gas/air mix in the particular triggered cylinder due to the potential to knock, or premature detonation of the air/fuel mix. This process saves the engine from damage/knocking at the expense of a tiny bit of power on 87.(But it is more significant with sub-87 octane and your car will run like garbage.)

In the end, if gas prices are like where I live, where 91 costs nearly $.50 more/gal than 87, then it likely is not worth it because the gained power is very minute and imperceptible. If 91 or 89 is cheap where you live, then I'd say go for it.

Hope this helps!
 

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I've got the 2.0L no tune, I've tried both regular and premium as the manual says I can use both. No difference at all, I just stick to premium since its only 25 cent (probably one cent in USD) difference per liter. Though my friends tell me they use regular on some gas stations and they notice knocking, they have no problems when using Shell though.
 

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*The Electrician*
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I've got the 2.0L no tune, I've tried both regular and premium as the manual says I can use both. No difference at all, I just stick to premium since its only 25 cent (probably one cent in USD) difference per liter. Though my friends tell me they use regular on some gas stations and they notice knocking, they have no problems when using Shell though.
Even cheap/low quality premium can cause issues. Always stick to good quality gas, know what your putting into your car. I tried premium for a month and went back to regular, zero difference noticed. The place I buy gas has their fuel pumped thru the same pipelines as jet fuel, no ethanol whatsoever goes thru those pipelines.
 

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I always use premium regardless of the car, even in my 1990s car, I'd use premium. I don't care honestly, it's like $2 more each time you fill up. It's inconsequential. I know if I run premium I don't have to worry. Our regular here in always mixed with 5-10% ethanol, and although they say that all new cars are fine with ethanol blends, I honestly don't trust the stuff. The reports of plastic elements deteriorating early is enough for me to pay the extra dollar and use premium.
 
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