I am just starting this topic, please add to it.
If you have a choice never use fuel with ethanol added.
No benefit to use premium fuel.
Be accurate when mixing oil and petrol.
Do not add more oil than is specified.
If you must store fuel, keep the container as full as possible before use.
Mix the oil and petrol only when you are ready to use it.
Stored mixed two stroke fuel, only has thirty days before it starts to deteriorate.
Wipe the top of the fuel container clean before pouring fuel into the tank.
Use synthetic oil rather than mineral oil.
Better to run the motor dry than leave fuel in the tank for extended periods.
Timely topic for me @Bundeenabouy. My relatively new 3hp runs, but has been gutless recently. It has struggled to get the RIB up on the plane, when it used to. And when it's been under full revs for a couple of minutes it sometimes slowly dies like it is choking because the breather cap is closed. I've been wondering if it's because I break every rule you listed. 
My favourite trick is to fill one of my two 10ltr jerry cans and add oil at the bowser, but months later when it's time to crack the lid on the full jerry, I wonder if there's oil and add a bit more just in case. So, the question is, where do I dump stale fuel? The question I've been wanting to ask for a couple of months is, how can I tell if my fuel has had oil added? Colour is a guide, but not definitive. And oily appearance is likewise. is there a sure-fire trick?
Select to expand quoteMarcoP said..
Timely topic for me @Bundeenabouy. My relatively new 3hp runs, but has been gutless recently. It has struggled to get the RIB up on the plane, when it used to. And when it's been under full revs for a couple of minutes it sometimes slowly dies like it is choking because the breather cap is closed. I've been wondering if it's because I break every rule you listed.
My favourite trick is to fill one of my two 10ltr jerry cans and add oil at the bowser, but months later when it's time to crack the lid on the full jerry, I wonder if there's oil and add a bit more just in case. So, the question is, where do I dump stale fuel? The question I've been wanting to ask for a couple of months is, how can I tell if my fuel has had oil added? Colour is a guide, but not definitive. And oily appearance is likewise. is there a sure-fire trick?
I used to do a similar thing to you, but we all hate a engine that does not run well, or worse will not start at all.
For me its worth sticking to the rules and my motor should outlast me.
Its like putting money in the bank. It will be there when you need it.
It will only take you an hour to service the carburettor, and it sounds and feels great when you have tuned it right.
You can learn a lot about your petrol oil mix from looking at the spark plug.
Good luck with it.
Can't say I've had a lot to do with 2stroke out boards but I've Had a lot to do with air cooled jobs, the ethonal blends are ok for more modern numbers but if your running an Ol girl proably best to steer away from it. Our modern lead free fuel doesn't seem to keep so well and I believe outboard mechanics have there work cut out for them at the start of the fishing season owing to fuel being left in tanks from last season. Not so much the 2stroke oil but the additives in the fuel deteriorate.
Mark your container very obviously and religiously put the oil in 1st that way there's no doubt ( + it mixes better)
water cooled 2strokes generally run with very little oil like 100:1 so if you got some fuel that's not so fresh feed it to your car or lawnmower, the cars fuel tank should be large enough to dilute it and as for the mower, it might blow some smoke,
my father taught me to turn the fuel off and let the two stoke engine stop that way .
I like to keep fuel in appropriate colored containers
Red - petrol
Yellow - diesel
Green - two stroke
So MarcoP when you grab the green container you know you've allready put oil in it
2 stroke mix can feel oily in your fingertips when you compare it to unmixed fuel.
Look for engine manufacturers details to determine the grade of fuel and the oil ratio.
Spark plug reading tells more about the air /fuel ratio so you shouldn't alter oil ratios to get a cleaner plug.
Cylinder head geometry and ignition timing are designed around a specific fuel grade,,,Higher octane rating fuels wont necessarily perform better in an engine that is designed to burn a fuel of a lower rating with a specific oil ratio and,,,even changing oil/fuel ratio changes compression therefore changes the way the fuel burns.
Don't believe that running the engine out of fuel to empty the fuel bowl can seize the engine, because of lack of oil lubrication,, as is sometimes circulated, That myth comes about from the shock cooling phenomena of when a two stroke runs out of fuel and the engine continues to be over driven by the transmission,,, the temperature of the engine cylinder drops rapidly altering clearances between moving parts within the engine resulting in seizure. more common in air cooled HP engines. (and air cooled aircraft engines when throttled right back during decent).
I have heard that using old two stroke mix in your car engine can mess with the O2 sensor. I would avoid it and use the old fuel elsewhere. You might be able to get away with it if it is just a small amount in each tank that is ultimately up to you.
I would advocate buying a syringe or mixer bottle. Fill Jerry to take with you if its a longer trip and only mix small amounts of 2 stroke fuel as required. you can then use the unmixed fuel in your car if needed.
As for ethanol - it is hydroscopic. it is probably fine in the short term but in a humid environment it might absorb water if stored for a lengthy period. Check the owners manual - i remember my last 2 stroke outboard which was a tohatsu/merc said no ethanol, in the owners manual.
Select to expand quoteJAKE123 said..
I have heard that using old two stroke mix in your car engine can mess with the O2 sensor. I would avoid it and use the old fuel elsewhere. You might be able to get away with it if it is just a small amount in each tank that is ultimately up to you.
I would advocate buying a syringe or mixer bottle. Fill Jerry to take with you if its a longer trip and only mix small amounts of 2 stroke fuel as required. you can then use the unmixed fuel in your car if needed.
As for ethanol - it is hydroscopic. it is probably fine in the short term but in a humid environment it might absorb water if stored for a lengthy period. Check the owners manual - i remember my last 2 stroke outboard which was a tohatsu/merc said no ethanol, in the owners manual.
I like the idea of using a syringe for oil measurement accuracy, certainly less messy
I agree with some of the above but modern car engines will not enjoy your 2st and will punish you. Old engines will be fine. As for marine 2st in mowers I've not tried it but have heard it's not good. Mowers are designed to run hotter so not good . YMMV
To test mixed or not , I've found wet a tissue and see if residue is left after the fuel evaporates. Not perfect , better to use a container that's only always mixed or use a bread tie when it's mixed and remove when it's not.
likewise run it dry as the carby bowl will evaporate leaving coloured gooey gel.
Last being pedantic hygro not hydroscopic. 
But yes ethanol has no place on a boat.
I try to buy 91 from Caltex, I think it probably has less ethanol but I have no proof of that. Never use higher than 91. I have tried synthetic oil but I think it's just dearer and works the same as mineral. Mix the oil at the lean end of the range. I used 40:1 with an older Evenrude 15
Select to expand quoteBundeenabuoy said..JAKE123 said..
I have heard that using old two stroke mix in your car engine can mess with the O2 sensor. I would avoid it and use the old fuel elsewhere. You might be able to get away with it if it is just a small amount in each tank that is ultimately up to you.
I would advocate buying a syringe or mixer bottle. Fill Jerry to take with you if its a longer trip and only mix small amounts of 2 stroke fuel as required. you can then use the unmixed fuel in your car if needed.
As for ethanol - it is hydroscopic. it is probably fine in the short term but in a humid environment it might absorb water if stored for a lengthy period. Check the owners manual - i remember my last 2 stroke outboard which was a tohatsu/merc said no ethanol, in the owners manual.
I like the idea of using a syringe for oil measurement accuracy, certainly less messy
Been doing that for years with the garden tools. Go to pharmacy and ask for largest they got without needle. $2
Yamaha sell a 2 stroke measuring bottle that has graduation on the side to shows you how much oil to put with how much fuel for 25,50 and 100 to 1
www.huntsmarine.com.au/products/yamaha-2-stroke-oil-measure-bottle-pn-oil-measu-re
Regards Don
Ok I should of specified modern fuel injected computerised cars proably wont appreciate a belly full of 2stroke, when I mentioned mowers I assumed everyone these day runs a brigs or a Honda 4 Stoke, and they will gobble just about anything,if your still running an Ol victa then I would add the appropriate oil on top of the outboard stuff. I guess most folk will only be mixing say 5L at a time and the 1L squeezey containers with the measurer on the side are the ducks nuts. As long as you RELIGIOUSLY ADD the OIL to the WELL MARKED CONTAINER 1ST (ie no oil no fuel ) no excuse then you can't go wrong.
Its kind of a moot point as there phasing the good Ol 2/ out anyway
Select to expand quoteBundeenabuoy said..
I am just starting this topic, please add to it.
If you have a choice never use fuel with ethanol added.
No benefit to use premium fuel.
Be accurate when mixing oil and petrol.
Do not add more oil than is specified.
If you must store fuel, keep the container as full as possible before use.
Mix the oil and petrol only when you are ready to use it.
Stored mixed two stroke fuel, only has thirty days before it starts to deteriorate.
Wipe the top of the fuel container clean before pouring fuel into the tank.
Use synthetic oil rather than mineral oil.
Better to run the motor dry than leave fuel in the tank for extended periods.
May I just add after running a 9.8 HP Tohatsu 2 stroke for the last 7 years as my cruising catamarans main engine and a 2.5HP 2 stroke as the dinghy motor for the last 20 years.
1
NEVER had a problem with ethanol in fuel. We cary 180 litres in 20L jerry cans. Fuel can be over 12 months old and still runs fine.
2
We pre-mix fuel with oil as soon as we buy it and before it goes aboard the boat. Its to hard at 2 AM to try and work out if the fuel has oil in it or not.
3
If we are leaving the boat for a month or two we will run the fuel out of the Carby by disconnecting the fuel line and letting the motor starve.
4
Learn how to strip your Carby and clean. Capsizing the dinghy in shore breaks on the South Coast makes this knowledge essential.
We have never bothered with a dedicated fuel filter /water sepperation system on the 9.8 and have used fuel from some pretty remote and dodgy suppliers with out issues. A 6 month strip and clean keeps things purring ( well more a ring ding dinging)
Select to expand quotegwiongwion said..Bundeenabuoy said..
I am just starting this topic, please add to it.
If you have a choice never use fuel with ethanol added.
No benefit to use premium fuel.
Be accurate when mixing oil and petrol.
Do not add more oil than is specified.
If you must store fuel, keep the container as full as possible before use.
Mix the oil and petrol only when you are ready to use it.
Stored mixed two stroke fuel, only has thirty days before it starts to deteriorate.
Wipe the top of the fuel container clean before pouring fuel into the tank.
Use synthetic oil rather than mineral oil.
Better to run the motor dry than leave fuel in the tank for extended periods.
May I just add after running a 9.8 HP Tohatsu 2 stroke for the last 7 years as my cruising catamarans main engine and a 2.5HP 2 stroke as the dinghy motor for the last 20 years.
1
NEVER had a problem with ethanol in fuel. We cary 180 litres in 20L jerry cans. Fuel can be over 12 months old and still runs fine.
2
We pre-mix fuel with oil as soon as we buy it and before it goes aboard the boat. Its to hard at 2 AM to try and work out if the fuel has oil in it or not.
3
If we are leaving the boat for a month or two we will run the fuel out of the Carby by disconnecting the fuel line and letting the motor starve.
4
Learn how to strip your Carby and clean. Capsizing the dinghy in shore breaks on the South Coast makes this knowledge essential.
We have never bothered with a dedicated fuel filter /water sepperation system on the 9.8 and have used fuel from some pretty remote and dodgy suppliers with out issues. A 6 month strip and clean keeps things purring ( well more a ring ding dinging)
I have both the Tohasu two stroke 4HP and the Tohasu two stroke 9.8HP.
Both have done approximately thirty hours.
I race my Swarbrick 26 with the 4HP and no separate fuel tank and and use the 9.8 HP when I'm not racing.
Probably a saving of 15KGs in weight.
I love both of them and have just cleaned the carby in the 4HP after thirty hour and it was as new.
Previously I had a Mercury two stroke 8HP and found water and orange goo in the carbs when I cleaned it.
How does your carby look when you clean it?
Select to expand quotegwiongwion said..
1
NEVER had a problem with ethanol in fuel. We cary 180 litres in 20L jerry cans. Fuel can be over 12 months old and still runs fine.
Yes it's best not to worry about ethanol. Any 91 you buy could have up to 9% of ethanol. The local garage in this South Coast village is an independent and they are flat out selling 91 to fishermen on their way offshore. I have never heard of any complaints. Ethanol is cheaper than petrol and it would be naive to think there is no ethanol in the stuff we buy. The ethanol factory is about 15ks from my place.
Select to expand quoteBundeenabuoy said..gwiongwion said..Bundeenabuoy said..
I am just starting this topic, please add to it.
If you have a choice never use fuel with ethanol added.
No benefit to use premium fuel.
Be accurate when mixing oil and petrol.
Do not add more oil than is specified.
If you must store fuel, keep the container as full as possible before use.
Mix the oil and petrol only when you are ready to use it.
Stored mixed two stroke fuel, only has thirty days before it starts to deteriorate.
Wipe the top of the fuel container clean before pouring fuel into the tank.
Use synthetic oil rather than mineral oil.
Better to run the motor dry than leave fuel in the tank for extended periods.
May I just add after running a 9.8 HP Tohatsu 2 stroke for the last 7 years as my cruising catamarans main engine and a 2.5HP 2 stroke as the dinghy motor for the last 20 years.
1
NEVER had a problem with ethanol in fuel. We cary 180 litres in 20L jerry cans. Fuel can be over 12 months old and still runs fine.
2
We pre-mix fuel with oil as soon as we buy it and before it goes aboard the boat. Its to hard at 2 AM to try and work out if the fuel has oil in it or not.
3
If we are leaving the boat for a month or two we will run the fuel out of the Carby by disconnecting the fuel line and letting the motor starve.
4
Learn how to strip your Carby and clean. Capsizing the dinghy in shore breaks on the South Coast makes this knowledge essential.
We have never bothered with a dedicated fuel filter /water sepperation system on the 9.8 and have used fuel from some pretty remote and dodgy suppliers with out issues. A 6 month strip and clean keeps things purring ( well more a ring ding dinging)
I have both the Tohasu two stroke 4HP and the Tohasu two stroke 9.8HP.
Both have done approximately thirty hours.
I race my Swarbrick 26 with the 4HP and no separate fuel tank and and use the 9.8 HP when I'm not racing.
Probably a saving of 15KGs in weight.
I love both of them and have just cleaned the carby in the 4HP after thirty hour and it was as new.
Previously I had a Mercury two stroke 8HP and found water and orange goo in the carbs when I cleaned it.
How does your carby look when you clean it?
It tends to get a small amount of fine gritty deposit in the bottom of the bowl.
The 2.5 is more problematic with the float valve jambing open.
The 2.5 carby is very simple (aka nasty cheap construction)
Have never seen a gooey deposit some describe.
Admittedly I have never run the non-sniff OPAL fuel that is/was? available in some of the indigenous communities.
Write on side of container the date fuel was put in it and date oil was put in it. Helps with Alzheimer's.
We use similar colour coding as Sunycoastguy, but add black for water.
When its stale, dont really know how to judge, that but after a year, in order to dispose of 4 litres of unknown I tried putting it in my 2004 Ford Terror while it had a nearly full tank of normal unleaded and no problem. The Terror didn't blink.
IT would be great to have an easy way to tell if the fuel had the oil in it or not. So far I tipped a bit in a glass and looked at its colour but the fuel itself comes in different colours. I will try the tissue idea above.
My Mercury 3.3 used to be hopeless, It would start on second pull but wouldn't accelerate and wanted to stop all
the time. I had to coax it along until it had run for 5 or 6 minutes, really annoying. The reason, apparently is because I
drain the carby. I took the engine to the service guy and complained about it and he said to leave the carby full.
So that's what I do now and there's no more trouble. Doesn't seem logical to me....but it works.
Select to expand quotesamsturdy said..
My Mercury 3.3 used to be hopeless, It would start on second pull but wouldn't accelerate and wanted to stop all
the time. I had to coax it along until it had run for 5 or 6 minutes, really annoying. The reason, apparently is because I
drain the carby. I took the engine to the service guy and complained about it and he said to leave the carby full.
So that's what I do now and there's no more trouble. Doesn't seem logical to me....but it works.
That's annoying, but better than having issues, and good you solved the problem.
Select to expand quotesamsturdy said..
My Mercury 3.3 used to be hopeless, It would start on second pull but wouldn't accelerate and wanted to stop all
the time. I had to coax it along until it had run for 5 or 6 minutes, really annoying. The reason, apparently is because I
drain the carby. I took the engine to the service guy and complained about it and he said to leave the carby full.
So that's what I do now and there's no more trouble. Doesn't seem logical to me....but it works.
If your motor takes 5 to 6 minutes to recover from running out of fuel then there is something wrong. Check the tank breather
The carby on my tohatsu 2.5 is a poor design for an outboard. When I tilt the outboard up, it drains some fuel out of the fuel bowl flooding the engine with a fuel rich mixture and then makes it really hard to start again. I have learnt to turn the fuel off as I'm heading ashore so that the engine runs out at about the time I would normally shut it off and tilt the motor,,, The motor then restarts dead easy. I have a walbro carby which I'm thinking of fitting which should be a cool fix
I used to have a 5hp Mercury two stroke for a while and l developed a routine of systematically doing the same procedure every time. I never ever kept petrol on board without mixing in the oil. Period.
After l got rid of it, for it was too heavy to lift it every time onto the holder plate on the stern, l replaced it with a four stroke 2hp Honda and never looked back. The mixing of oil was over and l never used adulterated - l mean the alcoholized fuels or E10 or whatever they call it - just clean unleaded usu 95 octane or so.
(The misguided use of the E10 concoction in my bike [DR650] caused the carby to gum up in a fashion never seen before. After a full carby service and replacement of all hoses and seals which became soft and gooey from that chemical soup called E10, the bike runs fine on plain unleaded, ever since.)
The little Honda always started second pull even after months of sleep. It lived on the stern with a cover over it. It was not necessary to drain the carby when stopped.
If any of you got problems with a two stroke and you used E10 in it before, you are bound to pull the carby down and clean it thoroughly with special attention to the float needle and bowl, and replacing all filters and rubber seals and hoses because they are eaten away by the WRONG FUEL as one never suppose to use E10 in an outboard motor! Despite all hype and bull!
Even if there are no visible signs of deterioration on fuel hoses they must be replaced because the damage has been done already by the chemical soup they call FUEL!?
