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I have a Mazda Axela 2009 2L. Is the engine desingned to be run on 91 octane or 95 octane? I was told by the car dealer that I should use 95 as it will give me better performance. Is it correct advice?

Our information shows this vehicle is designed to run on 91 octane fuel. You can also run the vehicle on 95 octane fuel if you like and it will likely give you a small increase in performance and improved fuel consumption but because of the price difference you are not likely to save any money.

Thanks for your prompt response. Is it safe to run on mixed fuel? I have a quarter of 91 left. If I fill it up with 95 does it do any harm to the engine?

My friend has a NZ new Nissan Maxima ST 2005 3.5L. She always fills it up with 98 or 95. Yesterday I accidently fill it up with 40L of 91. We feel the same when driving on normal road but heard a bit of noise when driving on the motorway. Will it be any issue to the engine? Thanks.

Different octane fuels can mix together OK so won't do any harm. If the vehicle is designed to run on 91, you're usually best to stick to that as there's generally no benefit in running a more expensive, higher octane fuel.

Thanks for your prompt reply and advice. I will stick to 91 for my car.

As to my friend's NZ new Nissan Maxima ST 2005 3.5L I understand that mixed octane is OK and won't do any harm to the engine which makes me feel a bit of relief. Can you also tell me is it designed for 91 or 95 octane fuel? Thanks.

The 2005 Nissan Maximais compatible with both fuels, just like your Mazda.
It can run 91 RON Octane and can be mixed with 95 without problems.

Same question, different car:
Which Octane fuel to use?

I've just bought a Japanese 2008 Honda Edix 2.0Litre
The dealer says that all cars run better on 95,
I'm skeptical, as I've just moved on from a very similar 2003 Honda Odyssey that I've run for ten years on 91.

I'm not sure where to look this up online, but I'm sure you good people do.