87, 89, or 91 octane?

[RabidRich]

So i recently purchased a new Mazda 3 GT...sweet ride, loving it. However I just noticed in the user manual (after a few fills of course) that it recommends 91 octane, and 87 should only be used in an emergency. When i speak to the dealer, they laugh and say the 87 is fine. Any thoughts on this one

[DragonZealot]

Go with the owner's manual.

The engineer who designed the engine is more knowledgeable than the nobody in the dealership.

[GoiNGPoSTaL]

Did you buy the MazdaSpeed 3 GT or just the regular Sport GT? If it's just the regular Sport GT are you sure you're reading the part about the Sport GT and not the Speed 3, most manuals have all the models in the same book?

[VorteC]

I doubt a normal Mazda3 needs 91 octane. Even if it does recommend 91, you will be able use 87, and maybe lose a little mileage.. but you save 10% @ the pump anyways :P

[skidz88]

Umm, go with the manual. It's a dumb question really. Eventually, using 87 will cost a lot of money when you need a new knock sensor and your motor is pinging. And you get poor gas milage. Now, is that really worth saving $5 at the pump?

[ES_Revenge]

The Mazda3 manual says to use 91 for a normal 2.0 or 2.3 engine? Are you sure you're not talking about RON (which is what they use in Japan and is different from our octane numbers here)?

91 RON is the same as 87 US/Canadian Pump Octane Number

[xg3]

been running 87 octane on my mazda 3 for 3 years..
i laugh too if u fill it up with 91.

[mr_raider]

From YOUR manual:

2.3-liter turbocharger engine
Your Mazda will perform best with fuel listed in the table.
Fuel Octane Rating* (Anti-knock index)

Premium unleaded fuel 91 [ (R+M)/2 method] or above (96 RON or above)

* U.S. federal law requires that octane ratings be posted on gasoline station pumps.

This vehicle is designed for and requires use of premium unleaded fuel. If 91 octane fuel [(R+M)/2 method] (96RON) is not available, gasoline as low as 87 octane [(R+M)/2method] (91RON) can be used temporarily for emergency purposes. Use of gasoline lower
than 91 octane [ (R+M)/2 method] (96RON) can decrease performance during its use.
Refueling the vehicle with the correct octane fuel a couple of times will restore vehicle performance.

Except 2.3-liter turbocharger engine

Your Mazda will perform best with fuel listed in the table.
Fuel Octane Rating* (Anti-knock index)
Regular unleaded fuel 87 [(R+M)/2 method] or above (91 RON or above)

* U.S. federal law requires that octane ratings be posted on gasoline station pumps.
Fuel with a rating lower than 87 octane (91 RON) could cause the emission control system
to lose effectiveness. It could also cause engine knocking and serious engine damage.

[tugzy]

REAR YOUR OWNERS MANUAL CAREFULLY... use what it recommends....done

[i3_dawg]

the user manual is your friend, but i think the mazda 3 2.3L n/a uses 87 octane. But its best to check with the manual.

[Pete_Coach]

As the others have said, read and follow th directions and instructions within the manual.
The reason fro using 91 octane is to ensure the engine performance is as per the specs. If you do choose for whatever reason to use a lower octane rating the ECU (engine control unit or whatever Mazda calls the computer) will detune the engine and cause you to lose performance and power. The computer does this almost immediately. It will program itself back once you return to using 91 but it will take several tanks fulls or 91 to get it working properly again.Yes, damage can be cause by prolonged use of the lower octane fuel.
This forum has had innumerable posts on octane in fuels so please search and read those rather than re-opening a very divisive and opinionated topic.

[Dixon007]

The MazdaSpeed 3 or 6 uses OCT 91
Regular mazda 3 such as 2.0 or 2.3 engines uses 87. i have my mom's manual book here and it says 87 for her 2005 mazda 3 . i think u have the mazdaspeed 3 book.
87

So i recently purchased a new Mazda 3 GT...sweet ride, loving it. However I just noticed in the user manual (after a few fills of course) that it recommends 91 octane, and 87 should only be used in an emergency. When i speak to the dealer, they laugh and say the 87 is fine. Any thoughts on this one

[malaco0219]

The MazdaSpeed 3 or 6 uses OCT 91
Regular mazda 3 such as 2.0 or 2.3 engines uses 87. i have my mom's manual book here and it says 87 for her 2005 mazda 3 . i think u have the mazdaspeed 3 book.
87

Correct me IF i'm wrong, I thought MS6 and MS3 require 93 Octance? Friend owns a MS6 and always complain about driving far to Sunoco to get 94, and sometimes he just gets 91 with octane booster.

I also remember Lumlum103 mentioning he said he used 91 once and experienced a power loss?

[KawaiiTentacleBeast]

MS3 is 91:

http://stg.mazdausa.com/MusaWeb/pdf/..._MAZDA3_QT.pdf

Apparently MS 6 needs 93 Octane.

[enforcerviper]

According to mazda usa... turbo model:

Use 91 octane or above premium unleaded gasoline only, extra fuel additives are NOT recommended

http://stg.mazdausa.com/MusaWeb/pdf/..._MAZDA3_QT.pdf