Fuel Mix - Mariner 5HP

On my old (2nd hand) Suzi 2hp the book says 100:1 so that's what I use.
In 30+ (maybe nearer 40) years it's never given me a problem, no starting issues, when I check the plug it's a nice golden brown and the telltale water is warm not hot, I've changed the plug once in that time.
I don't know how the engine has lasted!
 
Most engines have renagued on the 100-1 ... 100-1 was a knee-jerk reaction to the Greenies ...... most brands now have reverted to advising 50-1 ......

Which of course is not a problem as 2str are now old hat !!

Apart from the old Seagull and odd similar - 50-1 is now the ratio that just about covers most ... and your engine will thank you for it ...
 
Goldie said:
My (very) old Seagull was supposed to run on 10:1 - until I changed the jet ‘new one’ it cost me more in oil than petrol!
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Most Seagulls could run on 25-1 ......

To be honest I miss the old days of Seagulls ..... telling others in dinghy to look away and keep heads low as you pulled the cord !! That distinct sound .... and the rainbow wake left behind !!
 
Refueler said:
Most Seagulls could run on 25-1 ......

To be honest I miss the old days of Seagulls ..... telling others in dinghy to look away and keep heads low as you pulled the cord !! That distinct sound .... and the rainbow wake left behind !!
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I love simple 'stuff' so am instinctively a seagull enthusiast, but now I've seen how utterly simple a 'modern' 2T engine is I've realized even modern 2T outboards are already the least engine you can get away with so there just isn't a niche for Seagulls. (I still love 'em)

As someone who considered a vintage standing engine might be an interesting winter hobby I've concluded Outboards are even better. Simple, access is superb and you can clamp it at a comfortable height to work on. The perfect hobby engine and I happen to need it anyway.
 
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Refueler said:
Most Seagulls could run on 25-1 ......

To be honest I miss the old days of Seagulls ..... telling others in dinghy to look away and keep heads low as you pulled the cord !! That distinct sound .... and the rainbow wake left behind !!
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Yes, after the Seagull supplied mod kit, it did indeed run on 25:1
 
RichardS said:
any engine oil you use is going to be thicker than a modern two stroke oil so if viscosity were a prime consideration in the context of coating the internals then engine oil is probably going to be the better bet.
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Well... My biases are that this kind of thing is pure marketing and TCW-3 is not significantly different to anything else I'd buy. But top quality 2T oil is more money and will be designed with 2T GP racing bikes in mind which is a very different application to my outboard or my garden tools.

So if we assume different 2T oils make no difference, I might as well buy a TCW-3 which is cheaper. If we assume oil standard does make a difference I still might as well buy a TCW-3 'cos it's the 'right' oil for the job.

All academic because my accidental bulk buy of Oregon Semi Synth 2T oil will outlast the earth's supply of fossil fuels and my Dad used engine oil in our Yamaha 2hp and that engine was sold in perfect working order 30 abuse filled years after he bought it.
 
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TCW-3

I've checked the spec of the Oregon Semi Synth I currently use.

It meets ISO EGD, JASO FD, API TC. Essentially ISO EGD is the one that matters - if the oil meets ISO EGD it automatically beats the other two.

So my Semi Synth garden tool 2T oil meets the highest oil standards I can find.

Viscosity isn't mentioned anywhere. If viscosity was important wouldn't it be on the label?

It says on the bottle it can be used on ALL (their capitals) 2T engines. Obvs that's just marketing but maybe it carries some weight...


TC-W3 is a registered trademark. The "tests" include running it in 3 engines for 100 hours. Viscocity is not mentioned. No specific differences to the real standards are mentioned.

Certification - TC-W3

"The National Marine Manufacturers Association (NMMA) is the nation’s leading trade association representing boat, marine engine and accessory manufacturers." - It's a trade organisation, representing manufacturers, not consumers. It's has every reason to create a Mickey Mouse 'standard' to allow Chandlers to offer a commodity product at a larger margin.

So as far as I can tell TC-W3 is a total marketing ploy, any oil that meets the real standards would meet it. (Unless you think oil that meets ISO EGD would noticeably oil up or damage an engine in 100 hours!)

Anyone know better?
 
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Viking said:
Re: Fuel Mix -Measuring??

Ive just brought a Mariner 4hp.
The problem Im having is how the hell do you measure the oil into the petol? There are marks on the two stoke oil bottle in part lites into a gallon petol container. As anyone got a fool proof method? or is it all guess work?
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As a person who does like to run engines of the correct mixture but hates excessive smoke, I went to my local chemist and bought a small syringe in order that I can measure the exact amount of oil in CCs into the measured litreage of petrol, always remembering to filter the petrol before using it.

But a word of caution; the standard, medical syringe works well with oil of various grades,but the seal swells up and makes the syringe uselessly stiff if you get petrol in it.
 
langstonelayabout said:
As a person who does like to run engines of the correct mixture but hates excessive smoke, I went to my local chemist and bought a small syringe in order that I can measure the exact amount of oil in CCs into the measured litreage of petrol, always remembering to filter the petrol before using it.

But a word of caution; the standard, medical syringe works well with oil of various grades,but the seal swells up and makes the syringe uselessly stiff if you get petrol in it.
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I bought a set of measuring jars so I can get the mixture exactly right....

....then I add a bit for luck. ?
 
coveman said:
I've been advised by marine engineers to use a mix of 50:1 even if the manual says 100:1. There reasoning is that most two stroke engines are now quite elderly and the 50:1 ratio increases lubrication and hence engine wear.
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I think you probably meant to say that the 50:1 ratio increases lubrication and hence reduces engine wear.
 
2T oil is actually in basically 3 grades ... we'll ignore the sub divisions and marketing hype of some brands.

1. Formulated to be used in the HIGHER temperature engines where they are AIR-cooled.
2. Formulated to be used in the LOWER temperature engtines where they are WATER-cooled. Depending on brand - may also be treated to be more environmentally acceptable.
3. General Purpose 2T that can be run in both.

It is not advisable to run #2 in Air Cooled but you can run #1 in Water cooled. #3 of course is OK in all.

As to the 50-1 ratio ... as I posted before ... the environmentalists pushed for 2Str O/Bds to cut back on 2T mix and engines such as Mercury .. Mariner ... etc. changed to 100-1 mix. Problem was that in low load and cruise use - it was fine, but as soon as real work - the lack of lubrication soon hit home. The return to advising use of 50-1 was then made.
 
I disagree with it not being an exact science. If you increase the oil to petrol ratio, you effectively make the fuel leaner and two strokes are very sensitive to fuel/air ratio and you may have starting or idling problems. I ran my mariner on 50:1. I've reset my Seagull to 20:1.
 
ghostlymoron said:
I disagree with it not being an exact science. If you increase the oil to petrol ratio, you effectively make the fuel leaner and two strokes are very sensitive to fuel/air ratio and you may have starting or idling problems. I ran my mariner on 50:1. I've reset my Seagull to 20:1.
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I've often read that but my experience in the good old days was that carburettors were so imprecise that you could vary the fuel/oil ratio as much as you liked and the engine would still run more or less the same. With fuel injection the fuelling rates are a lot more precisely controlled, of course, but the software should be able to adjust the mixture on the fly anyway.

Richard
 
RichardS said:
I've often read that but my experience in the good old days was that carburettors were so imprecise that you could vary the fuel/oil ratio as much as you liked and the engine would still run more or less the same. With fuel injection the fuelling rates are a lot more precisely controlled, of course, but the software should be able to adjust the mixture on the fly anyway.

Richard
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Fuel Injection ?

The real decider now is with the separate OIL injection motors - where the 2T is adjusted separate to the fuel. But of course for the smaller runabout motors - we are still mixing before tank.
 
Refueler said:
Fuel Injection ?

The real decider now is with the separate OIL injection motors - where the 2T is adjusted separate to the fuel. But of course for the smaller runabout motors - we are still mixing before tank.
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I was making a general point about fuel injection in contrast to carburettors as you never see carburettors any more. I would have thought that modern two-stroke engine designs would use fuel injection although they are a somewhat specialised application these days so not within my orbit.

Some of the two strokes I used to work on were using separate oil delivery systems 40 years ago.

Richard
 
RichardS said:
I was making a general point about fuel injection in contrast to carburettors as you never see carburettors any more. I would have thought that modern two-stroke engine designs would use fuel injection although they are a somewhat specialised application these days so not within my orbit.

Some of the two strokes I used to work on were using separate oil delivery systems 40 years ago.

Richard
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Fuel Injection ..... on 2str ... makes me remember when I played with Wal-Philipps Fuel Injection on my Lambretta GT200 (bored out to 227cc).
 
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