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ronnietucker

petrol shelf life, and side effects?

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I've been reading that petrol has a 'shelf life' before it goes 'off'. Any idea what that shelf life is? I've had my petrol sitting idle (in petrol containers which serve the engine) for about 4 months over winter.

Also, if I was to still go ahead and use it, would it damage my outboard engine?

Any advice would be much appreciated  :)

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Maybe the more volatile compounds will have evaporated off making the engine more difficult to start but after just four months over winter I doubt you would notice. If you were talking four years then it might shed gummy stuff and block the carburettor. Two stroke mixture is worse in this respect.

Don't worry,  last week I ran my genny that had been sitting with petrol in it since last June.

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It can “got off”, due to evaporation of the lighter fractions. However, it can’t evaporate significantly if it is in a sealed container, and will go off more slowly in low temperatures. It will be fine in the outboard and worst case, the outboard won’t start very easily.

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As I now rarely use a chainsaw I often have premixed 2 stroke hanging around, it seems fine left for 6 months but I wouldn't use it any older,

Any unused, normally 5lts or less gets put in the cars tank, just prior to a fill up

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2 minutes ago, tree monkey said:

As I now rarely use a chainsaw I often have premixed 2 stroke hanging around, it seems fine left for 6 months but I wouldn't use it any older,

Any unused, normally 5lts or less gets put in the cars tank, just prior to a fill up

Last year I used up the last of a 3 year old container of 2-stroke mix in my chainsaw. Maybe a little more difficult to start and a wee bit more smoky, but it still worked. I then went out and bought another 5 litres of fuel which will no doubt sit around for two or three years too. 

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I use Briggs and Stratton 'fuel fit' for the petrol in my lawn mower. My mower usually starts on the first or second pull in the spring.

My neighbours doesn't, guess what he doesn't use?

Ok not entirely scientific but it's not expensive.

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Just now, WotEver said:

Last year I used up the last of a 3 year old container of 2-stroke mix in my chainsaw. Maybe a little more difficult to start and a wee bit more smoky, but it still worked. I then went out and bought another 5 litres of fuel which will no doubt sit around for two or three years too. 

I am sure it would be ok, as you have found but I like to give my saws a bit of tlc, just habit

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3 minutes ago, tree monkey said:

I am sure it would be ok, as you have found but I like to give my saws a bit of tlc, just habit

To use yet another Americanism... ‘natch :)

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4 minutes ago, WotEver said:

To use yet another Americanism... ‘natch :)

Best quality 2 stroke, alway clean after use, fluffy blanket to keep em warm, nice quiet corner so they can enjoy their retirement. 

Going too far?

:)

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12 minutes ago, tree monkey said:

Best quality 2 stroke, alway clean after use, fluffy blanket to keep em warm, nice quiet corner so they can enjoy their retirement. 

Going too far?

:)

Don't forget to run them dry thus avoiding a nasty case of gummedupitis .......... :P

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14 minutes ago, tree monkey said:

Best quality 2 stroke, alway clean after use, fluffy blanket to keep em warm, nice quiet corner so they can enjoy their retirement. 

Going too far?

:)

No bedtime story?

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Just now, Meanderingviking said:

Don't forget to run them dry thus avoiding a nasty case of gummedupitis .......... :P

Which I do of course

 

1 minute ago, WotEver said:

No bedtime story?

I leave the husky users manual with them, they enjoy a giggle

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1 minute ago, tree monkey said:

I leave the husky users manual with them, they enjoy a giggle

You’ll hurt my saw’s feelings. He’s a little Husky. 

I’ll beat the muppet to it... it’s all that old petrol that’s made him Husky ;)

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2 minutes ago, tree monkey said:

I leave the husky users manual with them, they enjoy a giggle

They're Stihl interested..............?

 

 

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1 hour ago, MJG said:

I use Briggs and Stratton 'fuel fit' for the petrol in my lawn mower. My mower usually starts on the first or second pull in the spring.

My neighbours doesn't, guess what he doesn't use?

Ok not entirely scientific but it's not expensive.

A second vote for the B&S mixture.

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My boat goes back in the water in April/May, always runs on fuel from last summer, 2 stroke mix. Done the same for the last 3 years.

My fuel is always at least 6 months old at the start of the season.

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I service a total of 10 saws & other kit for a earn a living from it logging set up The Us have  differentt amounts of Ethanol in petrol which caused bother over time to rubber parts in saws as far as I'm aware in France the petrol is almost E free the official fuel company's info recommends a 30 day shelf life but seems to work OK at a 3 or more month shelf life & Iv'e run a saw that had fuel in & had sat for a year the usual problem is failling to or very difficult to start  to the OP try your OB if it is slow to fire up change your fuel

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Apologies for missing the round of 'putting to bed jokes'.  I was talking to John Deer. Oh dear!

Two things to watch out for. Petrol (gasoline) contains a high proportion of olefins, unlike diesel, which is mainly paraffins. Olefins react to form gums. Speed of reaction doubles for every ten degrees of temp. Six months of storage in the Med can make it bad enough to block jets in small carbs. In the U.K. Maybe ok for a year if stored cold. Bear in mind, petrol is different depending how it is blended and some refineries may sell stuff more prone to gum formation.

Second issue is the light fractions Tony mentions above. Petrol is sold in 3 different grades. A winter, a summer and an intermediate. The winter grade will contain 10%+ of butane. The summer, less than half of that. This is done to get the RVP in the right spec (vapor pressure). If you fill your cans with winter grade then there is a lot of butane if you use it in the summer. It's not going to damage the engine BUT that butane vapor is the thing that kills people on boats. Make damn sure it is handled properly. Especially for Ronnie living near a refinery which stuffs the most butane in...of any U.K. refinery, it can be up to 15%. If on the other hand you have summer grade in the tank and use it in the winter, then the rvp will be low and maybe difficult to start, but a lot safer butane wise.

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14 hours ago, MJG said:

I use Briggs and Stratton 'fuel fit' for the petrol in my lawn mower. My mower usually starts on the first or second pull in the spring.

My neighbours doesn't, guess what he doesn't use?

Ok not entirely scientific but it's not expensive.

no additives used here (and usually old fuel)

mower starts 3rd pull (1st pull = nothing, 2nd pull = splutter, 3rd pull = running), this seems the same whether it's been 6 hours or 6 months since the last run

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My Kelvin starts on petrol, or rather a fierce mixture of oil and  petrol (1:16).  It doesn't seem to matter if I keep the petrol mix all winter as the biggest determinant of easy hand starting is to have clean plugs and a well set-up magneto and impulse drive.  Modern electronic ignition produces a much better spark so is less prone to suffer from plug fouling and will provide more  spark energy to get less volatile fuel lit.

An aircraft type igniter unit  ( 1 Joule sparks)  would be fun, but I don't know how one would time the bangs.

 

N

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If you outboard happens to be a Seagull then it just won't start on old petrol. I used to work with a load of old Seagull fanatics and they were always muttering "it will never start unless the petrol is fresh".

..............Dave

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9 minutes ago, dmr said:

If you outboard happens to be a Seagull then it just won't start on old petrol. I used to work with a load of old Seagull fanatics and they were always muttering "it will never start unless the petrol is fresh".

..............Dave

Probably means it needs the butane or C5's more than other systems i.e. a lower RVP.

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2 minutes ago, Dr Bob said:

Probably means it needs the butane or C5's more than other systems i.e. a lower RVP.

They are very emotional and sensitive engines, they also need the carburettor tickling and whiskers removing from the spark plug.

.............Dave

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