View Full Version : 91 vs 95 Octane

27-05-2008, 03:46 PM
Had one of those classic pub conversations-turned-arguments last night about newer vehicles that can run either octane rating actually being more economical on 95.

Theories abounded, but the consensus was that the engine didn't have to work as hard (on 95), so this more than offset the higher price-per-litre. . . .

What have you guys found?

27-05-2008, 03:49 PM
'93 Bluebird SR20.

I get a consistent 50km - 100km more off a tank of 95 rather than 91.

Better pick up, and smoother running also.

On the newer cars, I'm not so sure it makes as big of a difference.

Parents '92 Estima is the same again - and way better on 98 than 95.

Haven't really got a new car to test it on. :dogeye: But if you wanted to supply your Mazda for testing purposes... :p

27-05-2008, 03:59 PM
Yeah, well I was actually arguing the same as you Wrat - the Mazdagini does seem better on 95 (actually only run it on 95 when driving on long trips). Newer cars like mine have computerized timing/anti-knock adjustment etc so it can run just as well on either.

Might have to bust out the clipboard and white lab coat, and get all scientific n stuff!! :D

27-05-2008, 04:08 PM
I have a supercharged V6 and the manufacturer states I must run 95 to help stop pre-detonation....I get 10L to 100km on open road when using CC

27-05-2008, 06:47 PM
The only cars here in the US that actually REQUIRE high-test fuel are the Volvos...and maybe a RR and Ferrari or so.

I have a feeling that NZ octane ratings are NOT the same as US..because it's the law here that everything but some special (and I don't know why a Volvo is special!) cars must run on 87 R+M/2 rating.

Actually both 87 and 89 Octane rates will start a BBQ equally well if you can get them to burn.

27-05-2008, 10:11 PM
Well, anything with a turbo will probably benefit from the higher octane due to the high effective compression ratio with max boost; Most used imports seem to need it - I believe there is no fuel as low as 91 octane in Japan except for spirit stoves. If you conscientiously record your running costs for a few tankfuls of each grade you can soon tell which is the most cost effective. For my current car 96 is the best value, the previous one preferred 98. YMMV ;)