Petrol - I watch the pennies

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#2710675 21-May-2021 11:30

duckDecoy:

I don't know anything about this topic, but can I ask why people are saying that Gull 98 isn't any good compared to say BP? I always use 98 and buy it from my local Gull because it is always cheaper, even after the AA fuel discount. Should I not be??

And the reason I use 98 is because without it my 2005 Toyota Avensis (please be stolen today please be stolen today please be stolen today) can get stuttering from takeoff, which can be terrifying when you are leaving a stop or give way with another car bearing down on you. My friend was looking at buying one and the car inspector he hired happened to mention that you have to put 98 in it or it will stutter/stall , since then i always have and the problem completely disappeared. Every so often my partner will forget and put regular 91 in, and the problem returns.

The 'big 3' Share the same refinery and bulk storage. Gull do not. And import/blend their own. With alternate additives. Ethanol. Some engines, say don't touch ethanol. Hence all the references to using what the manual says. Not the sales pitches or performance car blogs. I think you will find with a quick search that model was a 2Lt+, small turbo/2L+ usually means Higher. While you'll find 1500/1600 can sit on the fence.

Jase2985

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#2710681 21-May-2021 11:44

Batman:

i have never seen a car manual that says use 98 fuel ...

so why should someone put 98 fuel in their car?

You probably wont find one either.

The people who use 98 are the ones who modify their cars to make more power and are pushing the limits of timing on their engines. the higher octane is more resistant to detonation so you can get more timing from the engine making more power.

Others using 98 think there may be a perceived benefit when there really isnt.

THere have been a lot of stores in Auckland at least that have removed their 95 pumps and put in 98 pumps giving consumers little other option other than go elsewhere or use 98.

eracode

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#2710687 21-May-2021 11:59

If I put 91 in a late-model three-cylinder 1.5 litre turbo where the manufacturer specifies or recommends 95, will it do any actual damage to the engine or is it just a performance issue?

Sometimes I just sit and think. Other times I just sit.

hsvhel

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#2710696 21-May-2021 12:19

eracode:

If I put 91 in a late-model three-cylinder 1.5 litre turbo where the manufacturer specifies or recommends 95, will it do any actual damage to the engine or is it just a performance issue?

It's likely going to retard the ignition if it hears knock. Providing it is late model enough to monitor the condition.

If it is late enough, you will loose some performance as the engine is not operating at peak. If it is not......bad things happen if left for too long

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Dingbatt

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#2710697 21-May-2021 12:24

Is it under warranty? If you knowingly use the incorrect fuel and the engine is damaged, you are giving the retailer an obvious out.

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Jase2985

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#2710698 21-May-2021 12:24

eracode:

If I put 91 in a late-model three-cylinder 1.5 litre turbo where the manufacturer specifies or recommends 95, will it do any actual damage to the engine or is it just a performance issue?

probably just loose a little performance

BlinkyBill

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#2710745 21-May-2021 12:26

Jase2985:

Batman:

i have never seen a car manual that says use 98 fuel ...

so why should someone put 98 fuel in their car?

You probably wont find one either.

The people who use 98 are the ones who modify their cars to make more power and are pushing the limits of timing on their engines. the higher octane is more resistant to detonation so you can get more timing from the engine making more power.

Others using 98 think there may be a perceived benefit when there really isnt.

...

Each of my Porsche’s manuals describe when to use 98. None of these cars are modified. There is a definite benefit to using 98 as indicated by Porsche.

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frankv

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#2710746 21-May-2021 12:27

duckDecoy:

I don't know anything about this topic, but can I ask why people are saying that Gull 98 isn't any good compared to say BP? I always use 98 and buy it from my local Gull because it is always cheaper, even after the AA fuel discount. Should I not be??

<tl,dr>Only the car's manufacturer knows what plastics and rubbers are used in its fuel system components, so only they can tell you if it is safe to use Gull 98 or not.

The issue with Gull 98 is the amount of ethanol in it. Ethanol reacts with some types of plastic and rubber. If your fuel system has these types of plastic or rubber (e.g. as seals or tubes or whatever) then those components will gradually dissolve or soften or swell. This will eventually result in a leak, which could mean that petrol leaks onto the ground, or onto a hot part of the engine, or air+fuel vapour leaks out, all of which can be dangerous. In addition, some fuel systems are pressurised... if the pressure is lost, your engine may not run properly. In one case I have seen, a fuel tank made from I think polyester resin (fibreglass) softened and deformed, as did fibreglass structure around it. This was a terribly expensive lesson for the owner.

eracode

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#2710751 21-May-2021 12:36

Dingbatt:

Is it under warranty? If you knowingly use the incorrect fuel and the engine is damaged, you are giving the retailer an obvious out.

Thanks but that is my question - will it cause damage? If not, this scenario is unlikely to arise.

It’s a new car for Mrs Code, being delivered next month.

It’s a serious question but I’m partly playing Devil’s advocate - just interested to know. We’ll almost certainly put 95 in it.

Sometimes I just sit and think. Other times I just sit.

Batman

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#2710767 21-May-2021 12:58

eracode:

If I put 91 in a late-model three-cylinder 1.5 litre turbo where the manufacturer specifies or recommends 95, will it do any actual damage to the engine or is it just a performance issue?

performance definite

damage depnds if the engine is smart enough to *detect knock. if it lets go ONE good knock bye bye engine - you'll know when that happens. apart from that, it's seems to remain a hypothetical risk. if you drive your car long enough and keep using 91 please update us though i'd like some data on this.

*detect knock means it will only do something after a knock happens to prevent future knocks. you hope the knock that it lets go is minor as you can't stop a knock. once that knock has happened it has happened. there is no crystal ball programmed into the car as far as i know ... though i could be wrong

Scott3

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#2710768 21-May-2021 12:58

Batman:

i have never seen a car manual that says use 98 fuel ...

so why should someone put 98 fuel in their car?

The toyota 86 would be one example: 98RON is recommended, with 95RON Minimum.

I.e. the engine is designed to run 98 (and the quoted power & efficiency numbers are based on this fuel). But in the event that you can't obtain 98, it is capable of running 95 (with reduced performance, and often worse economy) via an automatic limp mode without damaging the engine.

Many older JDM proformace cars are also set up for 98 (or higher) fuel.

Older Carbonated engine cars need to be run on whatever octane (or higher) fuel they were tuned for or they will be damage (no limp mode on these). "Performance" tunes generally set the car up so it gets the needs high octane fuel.

Modified engines are typically set up to make more power, but often require higher octane fuel as a result. an example of this would be a shaved block to increase engine compression.

And then there are some engines that can run fine on 91, but will make more power on 98. An example would be the 4.0 barra in a FG ford falcon:

91 RON is 195 kW and 391 Nm
95 RON is 201kW and 409 Nm
98 RON is 208kW and 420 Nm

Obviously some will feel the higher cost of higher octane fuel is well worth if for the 6 - 13kW extra power. Note that the barra is an unusual engine in that the difference is quite dramatic. Most engines have little if any difference.

duckDecoy:

I don't know anything about this topic, but can I ask why people are saying that Gull 98 isn't any good compared to say BP? I always use 98 and buy it from my local Gull because it is always cheaper, even after the AA fuel discount. Should I not be??

And the reason I use 98 is because without it my 2005 Toyota Avensis (please be stolen today please be stolen today please be stolen today) can get stuttering from takeoff, which can be terrifying when you are leaving a stop or give way with another car bearing down on you. My friend was looking at buying one and the car inspector he hired happened to mention that you have to put 98 in it or it will stutter/stall , since then i always have and the problem completely disappeared. Every so often my partner will forget and put regular 91 in, and the problem returns.

Gull 98 is actually E10. I.e. 10% ethanol.

Nothing wrong with this, but some older vehicles aren't compatible, and it isn't really suitable for lawnmowers and marine. Also it is hydroscopic, and quite an aggressive cleaner, so it is recommended that your first tank of it be a full tank, as that any water in the tank ends up being diluted in the maximum amount of ethonol.

Sadly the engine in the Avensis is one of the worst that Toyota has produced. If it runs well only on 98 I guess you are stuck with that fuel.

Scott3

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#2710771 21-May-2021 13:05

eracode:

Dingbatt:

Is it under warranty? If you knowingly use the incorrect fuel and the engine is damaged, you are giving the retailer an obvious out.

Thanks but that is my question - will it cause damage? If not, this scenario is unlikely to arise.

It’s a new car for Mrs Code, being delivered next month.

It’s a serious question but I’m partly playing Devil’s advocate - just interested to know. We’ll almost certainly put 95 in it.

Most cars sold in NZ recommending 95 will be able to run 91 without damage.

My BMW i3 had it in the manual: Recommended 95, Minimum 91 (if 95 not available).

In short the knock sensor will pick up the lesser fuel and alter timing to stop the engine from knocking (hopefully before any damage.)

Sometimes the limp mode is quite harsh, and results in really bad performance and excessive fuel consumption. There was somebody who reported this in a VW up that was imported used from the UK (where 95 is the lowest octane available), and the performance really sucked until they worked out they were fueling it wrong.

richms

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#2710782 21-May-2021 13:25

cshwone: Never used anything but 91 in my Sportage

91 in a high performance motor just cripples its performance. This is why you see so many nissan marches and similar driving so slowly and gutlessly around the place. No car made since the 90s should have 91 in it unless its a giant inefficient high displacement thing.

Richard rich.ms

richms

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#2710788 21-May-2021 13:36

eracode:

If I put 91 in a late-model three-cylinder 1.5 litre turbo where the manufacturer specifies or recommends 95, will it do any actual damage to the engine or is it just a performance issue?

Newer engines control the boost to quite a fine degree to protect the engine and economy and emmissions stuff. Put in crap fuel and you will find the turbo will be doing almost nothing. Put good stuff in and it will boost up to the design intention and give you good power and better economy.

Richard rich.ms

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#2710855 21-May-2021 14:25

richms:
cshwone: Never used anything but 91 in my Sportage

91 in a high performance motor just cripples its performance. This is why you see so many nissan marches and similar driving so slowly and gutlessly around the place. No car made since the 90s should have 91 in it unless its a giant inefficient high displacement thing.

The dyno tests I've seen in car videos show single digit difference in hp for NA engines. Don't think anyone's brave enough to dyno forced inductions on 91

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