is Super unleaded more stable / easy to ignite in 2 stroke?

jac

jac

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Having finally remembered to dispose of the remaining litre or so of 2 stroke it set me wondering.

We don't use a massive amount of outboard fuel - 1 5l can is plenty so will end up at the end of the season with some 6m old fuel to dispose of. I use fuel stabiliser but was wondering if using super unleaded would be any advantage over the regular.

I realise it won't suddenly make the dink plane but does it last longer and therefore remain more useable towards the end of the season or am i better off just buying small amounts more frequently.
 
I can't recall any starting problems developing by the end of the season with the 5 l that I buy in the Spring. I never use last year's mix in the outboard, though, it goes in my 4 stroke Honda mower.
 
jac said:
Having finally remembered to dispose of the remaining litre or so of 2 stroke it set me wondering.

We don't use a massive amount of outboard fuel - 1 5l can is plenty so will end up at the end of the season with some 6m old fuel to dispose of. I use fuel stabiliser but was wondering if using super unleaded would be any advantage over the regular.

I realise it won't suddenly make the dink plane but does it last longer and therefore remain more useable towards the end of the season or am i better off just buying small amounts more frequently.
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To the best of my knowledge no advantage in using super unleaded in a two stroke.

I always keep unused 2 stroke mix until the next spring, but always in full metal cans only to minimize contact with air, exposure to light and loss of the more highly volatile components.

I then use it mixed 50:50 with fresh or in the mower and the Seagull, with added oil as appropriate, both of which dislike stale fuel but are Ok with last years mix.

I always filter stored fuel before use, after one sorry incident which saw me stripping down a carb to clean it in the dark on a bouncy evening on one of the buoys outside Cowes.

Any in excess of what I can keep in full cans, which is likely to exceed 1 year in storage, or exceeds what I can legally store goes in the tank of a car which does not have a catalytic converter.
 
VicS said:
To the best of my knowledge no advantage in using super unleaded in a two stroke.

I always keep unused 2 stroke mix until the next spring, but always in full metal cans only to minimize contact with air, exposure to light and loss of the more highly volatile components.

I then use it mixed 50:50 with fresh or in the mower and the Seagull, with added oil as appropriate, both of which dislike stale fuel but are Ok with last years mix.

I always filter stored fuel before use, after one sorry incident which saw me stripping down a carb to clean it in the dark on a bouncy evening on one of the buoys outside Cowes.

Any in excess of what I can keep in full cans, which is likely to exceed 1 year in storage, or exceeds what I can legally store goes in the tank of a car which does not have a catalytic converter.
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Sound and sensible.....
 
Super unleaded has a higher octane rating like the old 4 star. Two strokes years ago used 2 star - lower octane rating. The octane rating being higher is a requirement for higher compression engines, which 2 strokes are not, so no benefit whatsoever to using super unleaded, and may worsen fuel economy as the fuel may not burn properly / efficiently. Indeed I am sure they offer it (notably at a higher price) for vain non-knowledgable idiots as a penis extension lubricant, as virtually all cars will run effectively and efficiently on the standard unleaded.
 
CFarr said:
Slight hijack :)
I'm just about to relaunch my new to me boat and there are some old cans of pre-mix fuel, 4star and diesel on board.
Where can I dispose of the fuel?
It's all at least two years old.
I'd like to keep the containers.
Thanks
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Use it. I laid up my VW van, diesel fuel, for seven years. Started immediately when I returned and ran on that fuel perfectly. I also had a strimmer with pre-mixed fuel in the tank, left for the same length of time. It also ran fine. Until a couple of days ago I was using a chainsaw whose fuel is certainly two years old, maybe more. Runs perfectly, although its tickover is perhaps a little erratic, runs slightly better on new fuel.

Provided the fuel is in closed cans it will not deteriorate in several years and even in my vented tanks has done OK.
 
vyv_cox said:
Use it. I laid up my VW van, diesel fuel, for seven years. Started immediately when I returned and ran on that fuel perfectly. I also had a strimmer with pre-mixed fuel in the tank, left for the same length of time. It also ran fine. Until a couple of days ago I was using a chainsaw whose fuel is certainly two years old, maybe more. Runs perfectly, although its tickover is perhaps a little erratic, runs slightly better on new fuel.

Provided the fuel is in closed cans it will not deteriorate in several years and even in my vented tanks has done OK.
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Use it with caution/ mixed with fresh perhaps. You may have been lucky but my Seagull does not run well on stale fuel and my Flymo just wont start. I suspect the trouble is loss of the more volatile components when not stored properly.

My big problem with the main outboard was i suspect due to deterioration of the oil.. God knows what happened but the last few ccs of one batch ( I forget what brand) would not even mix with the petrol. Just formed a jelly that was very difficult to filter out again.

Never heard of any problems with diesel ( apart from the "diesel bug") so not surprising your van started ok.
 
superheat6k said:
Super unleaded has a higher octane rating like the old 4 star. Two strokes years ago used 2 star - lower octane rating. The octane rating being higher is a requirement for higher compression engines, which 2 strokes are not, so no benefit whatsoever to using super unleaded, and may worsen fuel economy as the fuel may not burn properly / efficiently. Indeed I am sure they offer it (notably at a higher price) for vain non-knowledgable idiots as a penis extension lubricant, as virtually all cars will run effectively and efficiently on the standard unleaded.
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My Triumph Herald does 20% better mileage on super unleaded, compared to standard. I have no idea why this should be the case, since the compression ratio is not unduly high and the energy content of the fuels is the same, but I established the effect over many thousands of miles.
 
VicS said:
Use it with caution/ mixed with fresh perhaps. You may have been lucky but my Seagull does not run well on stale fuel ...
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My Seagull started and ran perfectly on a tank full of fuel which had been in it for 22 years. The tank had been well sealed, so I guess there just was';t anywhere for anything to go.
 
JumbleDuck said:
My Triumph Herald does 20% better mileage on super unleaded, compared to standard. I have no idea why this should be the case, since the compression ratio is not unduly high and the energy content of the fuels is the same, but I established the effect over many thousands of miles.
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My old Volvo does better on super unleaded too. Not proved over a huge mileage but enough to be sure.
At one time it was very iffy on ordinary unleaded so much so that while it was still available I ran on leaded 4*, then LRP or at the very least a mixture . Seems OK now but I dont know if the octane rating has been increased marginally or if quality control is better or if I have just managed to find the right settings.
 
VicS said:
When was it "invented" ? any idea?

I first heard about it in the mid to late 1960's in connection with gas turbine fuel storage.
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That's interesting. I have been peripherally involved with gas turbine fuel over the years, had plenty of problems with water (and drilling mud!) being delivered with fuel offshore but never met diesel bug. My van experience was 2003 when we returned home from Holland. Had heard of it before then but it didn't seem to be a recognised problem, although I had experienced 'sludge' in fuel on a delivery trip that was probably 1995.
 
vyv_cox said:
That's interesting. I have been peripherally involved with gas turbine fuel over the years, had plenty of problems with water (and drilling mud!) being delivered with fuel offshore but never met diesel bug. My van experience was 2003 when we returned home from Holland. Had heard of it before then but it didn't seem to be a recognised problem, although I had experienced 'sludge' in fuel on a delivery trip that was probably 1995.
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I was working at a site with 4x17.5 MW gas turbine generators, each powered IIRC with a RR Olympus jet engine, first coming into operation while I was there. In fact I can vaguely remember the initial trails. Although they were used for peak time electricity generation they were also used to start up the big cooling water pumps for the steam turbine plant on the same site.

There were some quite large storage tanks because the gas oil was also used for initial firing of the coal fired boilers for the main 350MW generators.

I can just remember our chief coming in one day and telling us that they had been alerted to the possibility of bacteria living at the interface between the oil and any water present. I guess it would have easily been dealt with by routine water/sludge draining.
I was only there for a short time so heard no more about it until hearing about "diesel bug" in boat diesel tanks.
 
VicS said:
I was working at a site with 4x17.5 MW gas turbine generators, each powered IIRC with a RR Olympus jet engine, first coming into operation while I was there. In fact I can vaguely remember the initial trails. Although they were used for peak time electricity generation they were also used to start up the big cooling water pumps for the steam turbine plant on the same site.
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Did you know that the Museum of Power (Internal Fire) in SW Wales, has a complete working Bristol Proteus powered generator set from a "pocket power station" on Dartmoor? It costs a pound a second to run, so they fire it up infrequently. I hope to see it running at one of their Crank Up days later this year.
 
My understanding is that super unleaded has a lower ethanol content (or even none at all with some brands) so it will keep better (ethanol evaporates faster over time than the petrol content) and also it is less likely to gum up your carbs on a two stroke. I run all my two stroke bikes on super unleaded, and the outboard fuel left over from the boat goes through them as well. I also use super unleaded in my race bike (big four stroke) because it only gets used a few times a year now and I don't want issues with stale fuel in the system. I don't have any fuel issues at all, where I did before someone told me about the ethanol and I changed to super unleaded.

Super unleaded has a higher octane rating than regular fuel. This isn't an issue for any of our engines. Octane slows the burn down so it's a longer release of energy and thus prevents the pinking you can get in higher performance engines, none of which is applicable to anything we use in boats (unless you're into serious powerboat racing....)
 
JumbleDuck said:
Did you know that the Museum of Power (Internal Fire) in SW Wales, has a complete working Bristol Proteus powered generator set from a "pocket power station" on Dartmoor? It costs a pound a second to run, so they fire it up infrequently. I hope to see it running at one of their Crank Up days later this year.
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No but thats interesting. Sadly not likely to be in the area but we used to go down that way for holidays at one time.
 
Triassic said:
My understanding is that super unleaded has a lower ethanol content (or even none at all with some brands) so it will keep better (ethanol evaporates faster over time than the petrol content) and also it is less likely to gum up your carbs on a two stroke. I run all my two stroke bikes on super unleaded, and the outboard fuel left over from the boat goes through them as well. I also use super unleaded in my race bike (big four stroke) because it only gets used a few times a year now and I don't want issues with stale fuel in the system. I don't have any fuel issues at all, where I did before someone told me about the ethanol and I changed to super unleaded.

Super unleaded has a higher octane rating than regular fuel. This isn't an issue for any of our engines. Octane slows the burn down so it's a longer release of energy and thus prevents the pinking you can get in higher performance engines, none of which is applicable to anything we use in boats (unless you're into serious powerboat racing....)
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lower ethanol content possibly of interest. Ethanol going to be a pita due to its effects on hoses, seals and diaphragms on older engines
 
VicS said:
No but thats interesting. Sadly not likely to be in the area but we used to go down that way for holidays at one time.
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It's geek heaven. Dozens of diesel engines, all runnable and mostly running, and a telephone display with two manual switchboards and five Strowgers all linked together and usable with a row of vintage phones. Well worth a trip to the wild west.
 
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