Best Gas Octane

[badboy916]

i just bought a 2003 miata and the owners manual had to be ordered. which grade of gas would you recommend? 87 or 89 or 91 octane.....please reply..thank you

[TR3-2001SE]

Starting in 2001 the Miata engine was designed to run on High Test or 91-93 octane. However it does have knock sensor and will adjust your timming if you use 89 or 87. I find a get much better milage with Shell V-power 93 octane. I can use the 89 but get a little less milage. It tends to knock on the 87 but I think given time to adjust it would run on it just fine just not as much power. Our compression ratio is 10:1 which is a little to high for 87 octane.