Stale Fuel

[philbolton]

Remember a few months ago in Evo they said the best fuel was from a busy garage as fuel goes stale! I share lifts to work now and my car can stand around for up to two days at a time, do you think the fuel will go stale in this time and end up being less responsive?

 

[alexbleubolt]

yeah mate, you can't leave your car for upto 2 days without using it, or it will not work. WTF....

 

[Fred@BTM]

doubt it, IIRC fuel takes a fair time to go dodgy

 

[Chris_H]

this is the most over hpyed b****cks in the industry.

By stale they mean it reverts back to standard 95 ron eventually.

Stale fuel I have yet to actually see a car that won't fire and run on 20 year old fuel. I drag em out all the time and "they haven't been started for 30 years son" and the 5 star thats still in it fires it up fine and drives away.

yes additive rich 95 will lose a coupel of points if left for a while but it won't make any noticeable difference to the car. Its all frankly a big placeabo and thus b****cks.

Like higher octane makes the car respond better, bull. You can have 90 RON fuels that the car will outrun 95.

Evos got to be the crappest mag out there for 'facts' like this

"the chassis dynamics and the smooth filling made the chocolate eclair slide easily into my gullet."

 

[Neil G]

I think you've hit the nail on the head Chris

 

[Day]

I'd be more worried about water getting into the fuel storage tanks myself.

 

[philbolton]

this is the most over hpyed b****cks in the industry.

By stale they mean it reverts back to standard 95 ron eventually.

Stale fuel I have yet to actually see a car that won't fire and run on 20 year old fuel. I drag em out all the time and "they haven't been started for 30 years son" and the 5 star thats still in it fires it up fine and drives away.

yes additive rich 95 will lose a coupel of points if left for a while but it won't make any noticeable difference to the car. Its all frankly a big placeabo and thus b****cks.

Like higher octane makes the car respond better, bull. You can have 90 RON fuels that the car will outrun 95.

Evos got to be the crappest mag out there for 'facts' like this

"the chassis dynamics and the smooth filling made the chocolate eclair slide easily into my gullet."

You think it could be instigated by the fuel companies to make people purchase the more expensive fuel, thus more profit for the robbing ba5tards?

 

[Alex_225]

Don't think the fuel being left for a couple of days would make it go particularly stale, not to any degree that you'll notice it.

But the whole RON thing does make a difference, the Megane 225s actually respond quite poorly with anything less thant 97RON in em, lumpy idle and going into 'limp mode'.

Won't do your car any harm leaving it a couple of days!!

 

[tidyclio]

Couple of days won't do any harm but i've seen an old Primera that had sat for about 4 months and the fuel did go stale the thing wouldn't start until we'd fired some more on so I wouldn't say it's a myth

 

[John D]

Think Evo mean it goes off a bit when its sitting in the big tanks beneath the petrol station, and over a longer period than 2 days! Besides even if something does evaporate off the fuel when its in your tank - wheres it going to go? its still trapped inside!

 

[tidyclio]

Yeah your right baldylocks but vapours seem to find a way out. Garagea have vapour release pipes so they are right.
It's a bit different as the tank isn't sealed aswell but i've got a petrol lawn mower and if leave it with fuel in it over a week when you go back to it and try and start it it won't do anything without fresh fuel the flash point is raised

 

[John D]

Slap some V-Power in that beast

 

[tidyclio]

Haha never thought of that shame the grass has stopped growing for the winter!
Theirs a video on Youtube of a guy that put hooked some NOS up to his lawnmower went like stink for about 5 seconds till it blew up in his face

 

[John D]

Yeah I've seen a couple of them. Seems to be a bit of a craze across the pond :S

 

[Chris_H]

why do people think fuel station tanks are like swimming pools underground?

An oil drum is 55 gallons. The undergound tanks are not even 5 times the size. You cannot walk upright in them or any of that crap,

They do have vent pipes.

The point is most fuel above 95 are actually 95 RON with additives.

Petrol mixtures change batch to batch, winter to summer.

RON is a rating to prevent knock, thats all, it doesnt mean your car will go faster, respond better or start easier.

I can give a more detailed exp later when I get home if you wish

 

[tidyclio]

My neighbour runs a Shell garage and it isn't the biggest garage they have 6 pumps and 6 tanks each is around 8000 litres so around 2000 gallons.

I understand what your say as I know the most volatile chemicals in fuel will evaporate first but what about 95ron fuel are you saying this wouldn't go stale?

 

[Toypop]

I think fuel takes a long time to go off? Over the winter I can sometimes go a month without riding the bike and it still starts and runs fine.

Others go for 3 or 4 months.

Can be a problem with modern fuels and carbs as it evaporates and leaves this really hard residue that requires the carbs to be totally stripped and cleaned.

 

[speedynz]

why do people think fuel station tanks are like swimming pools underground?

An oil drum is 55 gallons. The undergound tanks are not even 5 times the size. You cannot walk upright in them or any of that crap,

They do have vent pipes.

The point is most fuel above 95 are actually 95 RON with additives.

Petrol mixtures change batch to batch, winter to summer.

RON is a rating to prevent knock, thats all, it doesnt mean your car will go faster, respond better or start easier.




Chris, you sound like you know your stuff but I disagree about cars not performing any better on higher octane fuel.


I'll be blunt here, my Clio runs far harder and faster on 98 octane than on lower octane fuel, period.

My Cooper S loved 98 octane and my WRX Impreza would fly on it. All of these cars performed less satisfactorily on lower grade fuel.

You state that RON is a rating to prevent knock but fail to say that modern cars automatically adjust timing to suit the grade of fuel being used. It's that process that that either improves or degrades performance.

EVO magazine's assesment of different fuels may not have been the most scientific but it did unarguably show across the board power improvements when using the higher octane stuff.



I can give a more detailed exp later when I get home if you wish

 

[one_eight_two]

i left my 1.2 clio in the drive while i was in florida for 3 weeks started first time and no probs

 

[GordonD]

RON is a rating to prevent knock, thats all, it doesnt mean your car will go faster, respond better or start easier.

It is correct that higher octane fuel than an engine was designed for doesn't make it go any better. If you take an engine with a 9.0:1 CR designed for 90 octane, it won't go any better on 98 octane. A higher octane fuel only allows a higher compression ratio. Its not the fuel that results in the extra torque and power its the compression ratio. The octane rating only has to be high enough for the compression ratio.

But performance cars aren't designed that way any longer Chris. Cars these days have knock sensors and engine computers and high compression ratios. They're designed to take advantage of high octane fuels, but to back off their setting when you put lower octane fuel in. A car designed for 95 or 98 octane these days can run on 90 octane, but it produces less power.

Two stroke racing fuels , like for race karts, have a fairly short life because chemical reactions start when the oil and fuel are mixed. Ordinary two stroke fuels have a longer life because there's not much of a chemical reaction, but you're mixing two fluids and, given enough time, they start separating again like cream from milk based on density. Straight petrol is also a mixture of various hydrocarbons with different density and volatility, and the the lighter fractions evaporate faster. Those lighter fractions improve two things. Octane rating and cold starting in cold weather. That's what you lose with stale fuel. On a warm day with an engine that's easy to start and has a low compression ratio so it'll run on anything you wouldn't notice if the fuel was a year old. On a cold day you are going to notice. And in a modern engine that is designed for high octane you are going to have measurably less power and/or fuel economy.

 

[GordonD]

Here in Australia we have a fuel called "Opal" to solve a particular problem: petrol sniffing in remote aboriginal communities. Bored black kids in communities a huge distance from anywhere else get hold of petrol by either stealing it from visitors cars - the petrol bowsers are all locked in cages - or buying it, and they sniff it to get a high, and after a while it rots their brains. And if they are pregnant it rots the baby's brain.

So the oil companies developed a fuel that had an equivalent octane to standard unleaded without having any volatile components in it. It costs more to make a modern high octane fuel without the lighter hydrocarbons. So the government subsidises it for remote areas. And you can be prosecuted for bringing ordinary fuel - any more than is in your fuel tank - into those areas if the authorities think you are "trafficking" it to sell it to kids. They'll pay a fortune for it. Travel into the outback, put a couple of extra drums of fuel in the boot in case you run out in the middle of nowhere, and you can be prosecuted like a drug dealer.

 

[Neil G]

Here in Australia we have a fuel called "Opal" to solve a particular problem: petrol sniffing in remote aboriginal communities. Bored black kids in communities a huge distance from anywhere else get hold of petrol by either stealing it from visitors cars - the petrol bowsers are all locked in cages - or buying it, and they sniff it to get a high, and after a while it rots their brains. And if they are pregnant it rots the baby's brain.

So the oil companies developed a fuel that had an equivalent octane to standard unleaded without having any volatile components in it. It costs more to make a modern high octane fuel without the lighter hydrocarbons. So the government subsidises it for remote areas. And you can be prosecuted for bringing ordinary fuel - any more than is in your fuel tank - into those areas if the authorities think you are "trafficking" it to sell it to kids. They'll pay a fortune for it. Travel into the outback, put a couple of extra drums of fuel in the boot in case you run out in the middle of nowhere, and you can be prosecuted like a drug dealer.

Shocking stuff

 

[Chris_H]

Gordon, I am fully aware of fueling strategies and the wonder (lol) of knock sensing.

Ok since we all need to know a bit more,

2 fuels rated at 98 RON only have 1 thing in common, resistance to knock.

The 2 fuels can be very, very different in regards to consumption, response and power output.

A higher octance fuel can provide more power if theres a way that the higher octance fuel can be made use of. Even then its only an issue when knock is apparent.

Its simply foolish to say a car at 100% throttle, lightly loaded but accelerating will automatically do so quicker on 98 RON than 90 RON.

RON is regarded as a better indicator of a cars part throttle nknock resistance whereas MON (moto octance number) is a far better indicator of fuel throttle knock resistance.

To find out a fuels RON and MON numbers an single cylinder engine is used. It is calibrated with 2 pure fuels and then the test petrol.

The engine for the RON test has an inlet air temp of 65.6 deg c, engine coolant jacket temp of 100 deg c and the engine rpm is 600rpm.

The same engine for the MON test has an inlet air temp of 148.9 deg c, coolant jacket temp of 100 deg c and the engine runs at 900rpm.

The 2 calibration substances are mixed to match the blend of the fuel being tested. If the blend was 95% and then 5% of the other substance match the test fuel its 95 octane.

Good time to mention the american fuel, go to the pump and it may say 94 PON (pump octane number), the PON is worked out by adding the RON and MON together an dividing. 94 PON is actually 98 RON and 90 MON, so low octane yank juice as most europeans believe is a load of pish.

The difference between the MON and RON is the fuel sensitivity. A high RON number (say 100) but low MON number (say 90) would mean the fuel will act under heavy load or in a forced induction engine as a 90 octane fuel.

The fuels sensitivity can vary greatly. The RON may always be 98 but the mon could vary from 85 - 95 depending on additives used, the way it was stored and the quality of the crude that was cracked.

Avgas and other aviation fuels obviously run on higher than 100% pure substance mixtures, how is it made over 100%? They add lead to it.

Anyway this should give a basic insight into it and will show that 98 is NOT automatically better than normal 95 RON. theres lots more to it but its gets anal and is mostly about safe fual handling whch varies with the season btw.

 

[speedynz]

Lovely post Chris, a pleasure to read and very patiently and clearly put.

I do however have an issue concerning your statements.

The bottom line is that my Clio, my buddies Clio, My Cooper S, My WRX and almost everybody elses Clio will run noticeably quicker on 98 octane than on the lower grade stuff. Not just cleaner or sharper but clearly and figuratively quicker.

If your point is that 98 octane does not necessarily (in itself) make a car quicker then fair enough, but in every instance I've known of, in everyday domestic fuel pump terms, 98 octane is proven to produce more power than lower octane domestic fuel pump fuel.

As I stated in a previous post, EVO magazines comparison was not the most scientific but it gave unarguably clear results of greater power output using higher octane fuel.

 

[Chris_H]

I never said it won't make it quicker, I just said it won't always.

I remember a few very bad batch's of Optimax. I find BP to be better, esso seems to be better for mpg though.

It will make more power assuming the MPN is up which thanks to the additives it should be as they are sold as performance fuels. But they don't always!

 

[Sami]

Owned ^^

 

[Chris_H]

who has been 'owned'?

 

[John D]

I don't know either

 

[Chris_H]

perhaps its Sammi and the lack of understanding of the english language eh!

 

[welsh182]

I know nothing about the chemistry etc involved with Petrol.

However, I do know, my mover will absolutely refuse to start if not been used for a month or so, but put fresh petrol in it and it will start 1st try.

Also my old ZX6R which I crashed some years ago was in my garage for about 6 months with fuel in it before I repaired it, again, it would not start, put fresh fuel in it and it started in seconds.

 

[NORMY]

I worked for a while for an engeneering company where i spent my days servicing generator, mowers, and reconditioning engines.

from my experience small engines, like that of a mower, if left for a while the petrol does lose 'vapour'. the vapour being the main combusting part of the petrol. so smaller engines will find it harder to start on this. whereas a car should have no difficulty.
Also, i think this has already been said, mixtures such aspetrol and 2troke oils do 'spoil over timeand will cause starting problems.

alot of people will find a mower left fora month+, mostly true in winter, will have trouble starting it. unlessthey addsome fresh fuel. alot of mowers have 'primers'. rubber buttons that refesh the fuel in the feeds from the tank to the engine... and they do work!

So it is true, petrol can go 'stale', or lose a bit of its combusting properties over time. but a car shouldnt really be affected by this. unless its a really old banger thats been parked up in a field for 40 years with a quarter of a tank of petrol. its less likely to run, but probably still could!!