Toyspeed.org.nz Message Board

I just dropped the missus' Yaris down to Toyota for its 10k service. Was having a chat to the service manager and in conversation he asked what fuel I have been using.
I said 96 of course. (I always put in the best octane I can in whatever car except for old starlies )
He said that a car like that is designed to run on 91 octane.
I prefer to use 96, as sometimes at the pump, the fuel you're getting can be a few points lower anyway.
Conversation grew more as I wasn't giving an inch, he proceeded to show me in the owners manual that it says use 91 octane. I pointed out that it says MINIMUM fuel octane of 91. In other words, 91 octane is the bare minimum, right on the borderline.
I will continue to use 96, unless someone can explain to me why not too.

FYI Price is of no issuse, paying 2-3% more for a better product is a no-brainer IMO.

Your thoughts??

I put 98 in everything

I use what it says in the book. It all depends on how the motor is designed to run, no point putting more octane in than necessary. 12As run better on 91 and two stroke oil than 98 don't they?

Most of the modern ECUs will take advantage of higher Octane (they will advance ignition timing to increase efficiency).

i thought that higher octane is only really useful if the car absolutely requires it to avoid knocking, either due to high compression or forced induction, or the cars ecu is capable of adusting timing etc to suit a different fuels.
the higher octane just means that the fuel is actually harder to burn, so it only ignites when you want it to, ie spark , and not before while it is being compressed, as if it ignites then it burns unevenly in the combustion chamber and wastes energy.

econoboxes and commercials vehicles should only need 91, you may get slightly better milage due to the more efficient combustion but i doubt it would offset the extra cost.

cars with high compression run much nicer on higher octane and often require it, and the extra milage you get out of it offsets the cost of buying the more expensive fuel. we find a 2km/L difference on the open road between 96 and 98 in our caldina GT.

Yaris has 10.5:1 compression ratio (same as 20v silvertop), definitely has to be run on at least 96 to be efficient.
Most Japanese modern cars will run the best on 100 octane, some of them were designed to run only on 100 octane.

With Yaris, because it would retard ignition to run 91 it will underperform, so with 96 you will get better fuel economy, which should offset the price of the more expensive petrol (I even would bet it would be substantially more economical on 96 if you do normal driving - as in put foot down on the lights occasionally).

Thanks for confirming sergei.

ah didnt know the yaris ran that high compression

The Yaris engine is the same "power plant" that they use in the Sirions. For a 1.3L engine, they're pretty good.

I put 91 in it once. I didn't put it in again.

They're a good car though. You can give it death everywhere, get that "I'm such a hooligan" feeling, yet not be breaking laws

Pelo wrote:I use what it says in the book. It all depends on how the motor is designed to run, no point putting more octane in than necessary. 12As run better on 91 and two stroke oil than 98 don't they?

Apparently NA rotaries can run on as low as 76 octane fuel

as well as being harder to ignite, higher octane fuel also provides more power per litre, so if you drive conservatively it will provide better economy unless the car is specifically tuned for 91. particularly in jappas as sergei has pointed out, which are used to running on up to 100 octane.

imho buying 91 is a false economy in most cases.

Ive never run any of my cars on 91. Most have been performance cars, all have been jap imports. Even tho the primera is a nana car, im sure the SR18DE is tuned for 100+

rollaholic wrote:as well as being harder to ignite, higher octane fuel also provides more power per litre

Not necessarily - Ethanol has a much higher octane rating but also has a lower power density.

Octane rating deals strictly with how easy the fuel is to combust.

However, a fuel can be blended to also have higher power density and higher octane rating.

http://en.wikipedia.org/wiki/Octane_rating

Driveability and economy have both improved when I put my 4EFE Starlet from 91 to 95 octane gas.

i found no difference when i stuck bp98 in my ae111 4afe instead of 91... happily runs around on 91... and 530k's for $65

Didn't notice a difference when i put 98 into my 4k. Think ill stick to 91

use highest octane available - 95 to 98 on all my fuel injected cars.

used to put 91 in my 1995 falcon then started using 98, way better kms/tank, 50+ kms on average id guess.

i also started to use 98 in the carb'd corolla before I pulled it off road, it was nz new 1986 so, obviously it used to use leaded back in the day but has been changed for unleaded, (i'm actually unsure what this entailed) anyway it ran like a rocket, the 2e seemed to love it, though i'm unsure what damage/benefit it did for the engine itself.

We put 98 octane in our Vitz RS and it runs really well.

We also get just over 14kms per litre.

I only put it in as Toby said we should due to the compression ratios.