Old Fuel

[Skeets]

Always hear of motor manufacturers recommending the use of good clean new fuel with their motors.
My question is how old is old?
Is two week old fuel a problem?
Does movement prevent settling of fuel?
What do you guys think?

[joey_1987]

Hey, 2 weeks would be fine. When it starts approaching 2-3 months, then it starts to become a problem. Joey.

[Boz]

Hey Skeets

It really depends on a number of things including the type/shelflife of the fuel, where it is kept, what sort of container it is kept in, and there is probably a number of others that I havn't thought of.
Different fuels have a different shelf life but most should be good for at least six months if kept in an airtight sealed container and out of the weather.
I have had fuel with water in it after only a couple of weeks when I left my plastic fuel tanks in the boat which was out in the weather.
I have also had fuel in a sealed metal fuel tank on a motorbike for over 12 months, most of which was in the weather and the bike performed like the day i filled it up!
I have heard that some fuels like BP ultimate has a 12 month shelf life, but in the same respect Shell Optimax is only good for 3.
Also I have heard of some large fuel companies selling fuel near the end of its storage life to the independent service stations at a reduced cost, which would be fine if used within a certain time frame but would concern me if the fuel was to be stored.
I don't know how much of this is actually true as it is just what I have heard through people supposedly in the know, but it would be good if anybody had some actual facts on what type of fuel is the best for storing and how long the manufacurer recomends that you can store it for.

Boz.

[sf17fisherman]

i agree that some fule are fine for say 6 month and can say i have never had a problem with fule being three months old but this is sure one i would love to see the mythbusters do and put to bed for once and for all as i for one am still pretty much undecided

[Oldyella]

Put some Petrolpower Stabiliser (25ml per 100l) in it and it will control moisture and varnish. It will extend the life. Keep tank as full as possible to minimise evaporation. You can't get moisture in a full tank because the is no space. After 3 months, syphon 1/2 out and put it in the car. Top up with new fuel.

[marco]

Also I have heard of some large fuel companies selling fuel near the end of its storage life to the independent service stations at a reduced cost, which would be fine if used within a certain time frame but would concern me if the fuel was to be stored.


[/quote]


boz, the independent fuel tankers load from the same tanks as the major fuel company tankers / contractors , so that one is not true . also you can ring any of the labs at the refineries and get the low down straight from them , ive found them willing to help in the past .
cheers
mark

[Boz]

I have emailed a few of the major fuel companys this morning to find out what the recommended storage life of their fuels are, will let you know when I get a response.

marco,
As I said this was second hand information which actually came from someone I know who drives a truck for an oil company and is mates with someone who drives a fuel truck for a different company. How reliable this information actually is I don't know but honestly nothing would supprise me!

The most important thing to remember though is to keep your fuel in a sealed airtight container and out of the weather and a couple of months shouldn't be a problem.

[Boz]

Have got my first reply from Shell, who also recommend against the use of optimax for marine engines.

The life of petrol stored in airtight conditions with minimal variation in temperature(inside and not in direct sunlight) can be from 3-6 months.
Shell Unleaded 95 would be a better fuel for marine 2 stroke engines, as the higher density of Optimax combined with the cooler running of marine 2 stroke engines, can result in the engine running too rich and plug fouling. In any case, you would be unlikely to see a performance benefit unless the engine was higher compression and/or tuned for 98 RON fuel.


This was their response, hope it helps.

[marco]

hey boz , i wasnt having a shot at ya , i just know when i go and load there isnt a seperate loading arm that says independent crap fuel here lol it's all the same stuff and as for brissy it comes from eithier bp or caltex .

thanks for the info and as a foot note to optimax , if your putting it in a fuel system that has done a few miles blend some unleaded with the optimax for the first tank as optimax has a strong cleaning aditive that can block fuel systems on the first run . my first tank in the car resulted in car stopping after 14 kms and a 600 dollar bill to follow for blocked injectors . shell was kind enough to pay the bill on that one . in saying that i dont run it in the boat .

cheers
mark

[Pwoida]

Bear in mind that petrol mixed with oil has a much shorter shelf life than petrol on its own.

[Boz]

Ok, just got a response from BP. You may find this to be quite interesting as they never actually give a time frame for fuel to become stale, but never the less has some good information in it.

Where petrol is kept for more than a week in a vehicle tank special considerations apply because that petrol will change with time. Examples are classic cars and bikes, veteran and vintage cars and bikes, racing cars and bikes, drag cars, boats, dual fuel vehicles etc.


HOW PETROL CHANGES
To understand what the potential implications are it is necessary to understand how petrol changes with time. In the fuel tank of a car exposed to the air the volatile components of the petrol will evaporate, these volatile components contain high octane compounds so the octane of the petrol will fall leading to pinging (knocking).

The volatile components have low density so as they evaporate the density of the remaining petrol increases, this will change the way the carburettor float sits so that the engine starts to run rich at all times, this will lead to overfuelling and carbon buildup. The remaining high density components have a high carbon content that promotes carbon fouling on spark plugs and they are hard to ignite so causing misfire, hesitation and stumbling. The petrol will oxidise in air forming gums that can clog jets, the sulphur compounds in the petrol will react with copper and brass components to form brown varnishes that clog the jets on the carburettors, affecting fuel air mixture and causing poor running.

The time that fuel takes to go off in a fuel tank depends upon the temperature, fuel and conditions, nominally it could take 1 week for octane loss to show, gum formation and sulphur attack is continual leading to a steady build up of gum and varnish.


HOW BP ULTIMATE HELPS
BP Ultimate has the following properties which help where vehicles are used only intermittently.

1) Low Sulphur –BP Ultimate has the lowest sulphur and this reduces attack on brass and copper components.
2) Metal Deactivator- BP Ultimate contains an additive called a metal deactivator that protects copper and brass components from corrosive attack.
3) Anti Oxidant – BP Ultimate contains an anti oxidant that protests the fuel and stops it oxidising and forming gums.
4) Corrosion Inhibitor – BP Ultimate contains a corrosion inhibitor that protects steel and iron surfaces from attack by water droplets and humidity.
5) Powerful Detergent – BP Ultimate contains a powerful detergent to keep inlet valves and fuel systems clean and remove build up of gums and varnishes.
6) High Octane – the 98 octane of BP Ultimate means that if octane is lost through evaporation of lighter components it does not reduce to the point where it can become a concern.


MAINTAINING FUEL IN VEHICLE TANKS
It is not possible to provide a foolproof strategy for vehicles that are used only intermittently, however the following principles help.

1) Always add at least a quarter tank of fresh fuel when the equipment is to be used when it has not been used for more than a week.
2) Always keep the tank half full to stop water vapour from being sucked in and condensing.
3) Use a high octane fuel.
4) Use a fuel that contains anti oxidants, metal deactivators and corrosion inhibitors to protect metal surfaces.


Sounds like a good ad for Bp Ultimate to me!!!