NB8 91 or 95 ron fuel?

[nick viner]

All I know is that the only time I used BP e10 by mistake my 2002 NB ran like crap. I will NEVER put that in the tank again.
Cheers Nick.

[NitroDann]

As my previous post explains. The rumours that its crap are plain wrong, its that your car wasnt tuned for a fuel with such a high stoichiometric ratio. In other words its like claiming that nitromethane is crap cos mums camry wont even start on it. You know?

Dann

[Locutus]

I'm not sure of the factory (handbook) minimum recommended RON for the SP or SE.

the SP doesn't have it's own handbook - it was delivered with the standard NB8B owner's manual.

i didn't know NB8Bs were supposed to have a diet of 95+ RON. There is a sticker on the inside of my fuel flap which says minimum 95 RON, but i assumed that was an SP thing - do 'standard' NB8Bs have that sticker too?

[r_muir86]

I'm not sure of the factory (handbook) minimum recommended RON for the SP or SE.

the SP doesn't have it's own handbook - it was delivered with the standard NB8B owner's manual.

i didn't know NB8Bs were supposed to have a diet of 95+ RON. There is a sticker on the inside of my fuel flap which says minimum 95 RON, but i assumed that was an SP thing - do 'standard' NB8Bs have that sticker too?

In answer to your question, yes, my standard 2000 model NB8B also has this sticker.

[Old Dude]

Interesting how manufacturers decide what is suitable fuel..........I have a 2008 X trail, that Nissan told me do not run it on E10, now you would think that such a relative new car it would be designed to run on E10

Cheers
Dale

Question for those in the know, is E10 a higher octane than 91? I was told it was because ethnol is higher octane. But I would really like to know for sure.

The guys at Nissan told me that the Xtrail didn't use E10 because it made the motor run too hot maybe its as Dann says, its runs hot because its not tuned for it?

cheers
Dale

[NitroDann]

Pure ethanol has a stoichiometric ratio around 7:1 where petrol is 14.7:1.

This means it takes 7 parts air to each part fuel rather than 14 parts. Basically double.

If you add e10 and the car has no way of knowing it just wont add that extra bit of fuel it really should have. This is called lean (too much fuel is rich, or colloquialy, fat) and causes a much hotter burn.

Dann

[Quicksilver]

The NB8A owners manual states on page 3-2 "Your Mazda will perform best with regular unleaded fuel having a research octane number of at least 90." I guess this means that 91, 95, 98 octane should all be okay according to Mazda. Interestingly I havent found any warning in the manual against ethanol but maybe that evil substance wasn't so widespread available in the late 1990s.

I havent honestly found much difference in economy using different octanes (7.5-8.5 l/100k) and my car is mostly used for Sunday cruises so shaving off micro-seconds on track time doesnt apply for me but I generally use 95 as the consencus on this forum seems to be that higher is always better. I'll take your word for it!

A side question though: I sometimes have filled with 91 when high octane is a lot more expensive then topped up with 95 or 98 when the price is more reasonable. Are there any issues with mixing half and half of different octanes? Do they mix and average out or are there issues for the engine management system?

[Apu]

You've got to be pretty anal for it to "matter". Like Dann said, if the manufacturer says minimum 91 octane, it's not going to make any difference if you run 95 or 98. It's only going to matter if you belt the daylights out of the car.

I have run lower than recommended octane fuels simply because the higher octane stuff wasn't available. The car still ran fine until you revved it - but with most modern day cars, the knock sensors take care of it and retard things so all that happens is a "loss" in power. Topped it up with the higher octane stuff, and all was good again.

[NitroDann]

You cannot possibly make more power just by changing octane levels. Octane ONLY measures knock resistance, it doesnt measure energy output when burned(calorific value).

If higher octane fuel is added the timing can be increased (higher octane actually burns slower, advancing timing starts the burn earlier to make up for this). For various reasons beyond the scope here, this will result in better torque.

Just adding a fuel with greater octane will change nothing except increase knock resistance.

All regular petrol is mixable thats correct.

Dann

[Apu]

Just to clarify...

Again, as Dann says, you don't make more power with a higher octane petrol. However, you do "lose" power if a use a lower than recommended octane level...and you'll hear some interesting noises as well.

[NitroDann]

More specifically, if you use a fuel with a knock resistance below whats required, youll cause detonation (knock, pre-ignition, pinging).
This is very damaging and if you have knock sensor equiped car it will reduce timing, and power, hopefully soon enough to save your ring lands.

Dann

[Mr Morlock]

Taking the manuf recommendation seems a good choice. Quicksilver made some observations about fuels 91 95 etc. "Drive" did a test of identical cars , same route and rotated the drivers using E10, 91 and 95. It therefore was a real world situation with an effort to replicate what are the differences. They of course considered the cost ( cpl) versus the economy ( l/100) which then gives the best value for trip distance and $. Worst result was E10 then 95 then 91.

[Hjt]

the SP doesn't have it's own handbook - it was delivered with the standard NB8B owner's manual.

And as i found out today, a boost gauge is also lacking.

Best to stick to the recommended fuel, personally i run RON98 and at worst 95. My timing is advanced so i would rather run out of fuel than use 91 at the moment.

We have a 2009 Toyota Yaris at my work, recommended 91' but it pings under high revs, my employer would rather save a few dollars on fuel per tank, and repair the engine when it seizes, rather than proper maintenance.

As mentioned earlier, unless you get your vehicle tuned for a specific blend, just play it safe, it's worth the 5 dollars more per tank you get so much more for 15 cents per litre.




PS Next time your at the pump, read the litres sold/used on the machine your filling at, E10 is usually way in-front of any other blend, i feel sorry for some vehicles out there, and i bet the mechanics love it.

[Locutus]

We have a 2009 Toyota Yaris at my work, recommended 91' but it pings under high revs, my employer would rather save a few dollars on fuel per tank, and repair the engine when it seizes, rather than proper maintenance.

you will actually save money by filling the yaris up on 95. cost is approx 10% more, but you will get around 20% more kms. there is quite a noteicable difference in mid range torque too.

about 4 years ago i managed a hair under 6L/100kms in my YRS manual on mobil 95 while using purely as a daily in sydney peak hr traffic.

[NitroDann]

I think some of you will find you have a few misconceptions.

Yes Its true that you require more e10 for the car to run at stoich. But your car doesnt know this and wont inject any more or less fuel per ignition event so your fuel useage wont change because of it.

Of course if your car makes more torque on a particular fuel, youll use less throttle and therefore save fuel, but going to a higher octane fuel with no other changes wont benefit your torque production in any way.

You might see mileage improvements from one fuel to the other but this is purely due to calorific value. Think calories in food, its exactly the same. A glass of coke contains more energy (kilojoules, calories) to walk a certain distance than a glass of water, and a higher calorific value fuel is the same.

The best reason to use bp ultimate is not the octane (although if your experiencing detonation on an inferior fuel thats the reason) but because of the additive and detergent package included, along with the knowledge that it will be clean and grit free, certaintly in comparison to the no name bloke around the corner with the 30 year old pumps and 50 year old rust laden tank.

Dann