2 stroke oil has disadvantages.

[John Engineer]

Dear Readers and those that have left comments on this post.

My many years of experience with 2 strokes (good or bad) and the efforts of the best engine manufacturers are still up against climate change.
4 stroke still has pollution disadvantages but can run on LPG (original designed or conversion) This lowers the emissions by around 50% so that is what we should be looking at in reality.
I think these 2 pages of discussion should be enough for the average yachtsman to decide for him/her self what to do now.
I will no longer post open advice to everyone about "disadvantages of 2 stroke oil" due to the realistic argument that they are filthy polluting engines irrespective of the type of oil used.
Kind regards to you all!
John.

[gamayun]

John Engineer, I appreciate this thread for the very reason that I was recently wondering what oil to use for an old 5 hp Yamaha 2-stroke engine. I had just purchased this little sailboat and was going out for a test ride. I popped into our local small boat shop looking for something else when I asked the guy at the back about using SAE30 oil. He looked at me funny like he'd never heard of such a thing and said "there's 2-stroke oil made for 2-stroke engines." I said, "oh, thanks!" and just went on my way, but feeling a little sheepish. It's not like I didn't do a bit of research on the subject beforehand, but I'd been concerned ever since that I might be messing up my outboard. It belches a little smoke and fuel on start up, but runs just fine after a minute though I've only used it a few of times because we recently dropped the mast to replace the rigging. It had sat with old fuel and had not been run for a long time before I bought the boat with friends in a lien sale. From this thread, I will start to rest more easy though I probably would have been a little more cautious if I'd just slapped down big bucks for a shiny new engine!

[gamayun]

Originally Posted by John Engineer

By stopping with a "FOG" (non evaporating oil based spray) (Not WD40) the surfaces are better protected.

Could you also explain what you mean by stopping with a FOG?

[Lake-Effect]

Originally Posted by gamayun

Could you also explain what you mean by stopping with a FOG?

At the risk of mansplaining, I believe he was just referring to fogging.

"Fogging" is an oily spray used to protect outboards from corrosion when storing them for the winter. You pull the spark-plugs and spray it into the cylinders.

[gamayun]

Originally Posted by Lake-Effect

At the risk of mansplaining, I believe he was just referring to fogging.

"Fogging" is an oily spray used to protect outboards from corrosion when storing them for the winter. You pull the spark-plugs and spray it into the cylinders.

Good to know and happy to never have to do this!

[Lake-Effect]

Originally Posted by gamayun

Good to know and happy to never have to do this!

Sure, rub it in...

[a64pilot]

Originally Posted by gamayun

Good to know and happy to never have to do this!

If you ever put up any engine for storage, you should. Any piston engine anyway.

[Rumpi]

I find the thread interesting but very disorganised so I'll try to structure my post:

1. Carburator varnishing:
This is a function of gasoline evaporating. It will happen regardless of oil presence or type of oil given enough time. If this would not be the case one would never have to clean a 4stroke carburator. Oil just colours it and adds more solids to the mix. How soon the varnish forms depends on what is in the gas and the oil and how quick this things oxidize and polimerize after the volatiles have left.

2. Using "normal" oil:
Yes it's possible to use straight mineral oil or blended motor oils in 2stroke motors. In fact 2 stroke oils are often mineral oil based. The first problem is that mineral oils have high ash content after burning. The second problem is that mineral oils have a high flash point and will not burn completly. When using mineral oils the usual problem is a oil rich exhaust (leading to gum formation) and coke in the combustion chamber (including piston top). To solve this issues outboard motors use oils formulated with very low flashpoints and very low ash. Most of this oils are now fully synthetic, meaning they were build up from the individual components and not obtained trough distillation of crude oil and then blended with additives. They usually are also biodegradable so even if unburned oil escapes down the exhaust it will not pollute.
Every flavour of oil has its advantages and disadvantages:
a) straight mineral oil (SAE30 and similar):
+ high flashpoint.
- high coke formation, very oil rich exhaust
b) blended mineral oil (20W40 and similar 4stroke engine oil, semi-synthetic 2 stroke oil for air cooled motors)
+ high flashpoint, low coke
- high ash, oil rich exhaust
c) fully synthetic outboard oil
+ very low ash, biodegradable, no coke
- low to very low flashpoint
d) fully synthetic high performance oil
+ very high flashpoint, low to very low ash, no coke
- not always available everywhere, more expensive
e) castor oil
+ very high flash point, oil is attracted to high temperature spots
- very high coke and gum formation

What you choose depends on what motor you have. Stock water cooled outboard motors are best served with a fully synthetic outboard oil. The reasons are pollution and coke. Air cooled motors should always use a high flashpoint oil. When using high flashpoint oils it's better to go for one formulated for 2stroke use since it will have less ash. Thermally challanged motors should use only very high flashpoint oil.

3. Carburator jetting:
Different oil have different viscosity and this affects carburator jetting and settings. This effect is more evident when switching between straight mineral and full synthetic. Normal people should use whatever type oil the manufacturer said. When dealing with really old outboards one has to experiment to find the right jets and settings (or pay someone to do it).

4. LPG (propane):
Any 2stroke motor with separate lubrification (Autolube and similar) can run on propane. The problem is normally finding a kit designed for small displacements and heating the gas. Bigger displacement engines are more easy to convert.

[skipmac]

Originally Posted by Rumpi

I find the thread interesting but very disorganised so I'll try to structure my post:

1. Carburator varnishing:
This is a function of gasoline evaporating. It will happen regardless of oil presence or type of oil given enough time. If this would not be the case one would never have to clean a 4stroke carburator. Oil just colours it and adds more solids to the mix. How soon the varnish forms depends on what is in the gas and the oil and how quick this things oxidize and polimerize after the volatiles have left.

2. Using "normal" oil:
Yes it's possible to use straight mineral oil or blended motor oils in 2stroke motors. In fact 2 stroke oils are often mineral oil based. The first problem is that mineral oils have high ash content after burning. The second problem is that mineral oils have a high flash point and will not burn completly. When using mineral oils the usual problem is a oil rich exhaust (leading to gum formation) and coke in the combustion chamber (including piston top). To solve this issues outboard motors use oils formulated with very low flashpoints and very low ash. Most of this oils are now fully synthetic, meaning they were build up from the individual components and not obtained trough distillation of crude oil and then blended with additives. They usually are also biodegradable so even if unburned oil escapes down the exhaust it will not pollute.
Every flavour of oil has its advantages and disadvantages:
a) straight mineral oil (SAE30 and similar):
+ high flashpoint.
- high coke formation, very oil rich exhaust
b) blended mineral oil (20W40 and similar 4stroke engine oil, semi-synthetic 2 stroke oil for air cooled motors)
+ high flashpoint, low coke
- high ash, oil rich exhaust
c) fully synthetic outboard oil
+ very low ash, biodegradable, no coke
- low to very low flashpoint
d) fully synthetic high performance oil
+ very high flashpoint, low to very low ash, no coke
- not always available everywhere, more expensive
e) castor oil
+ very high flash point, oil is attracted to high temperature spots
- very high coke and gum formation

What you choose depends on what motor you have. Stock water cooled outboard motors are best served with a fully synthetic outboard oil. The reasons are pollution and coke. Air cooled motors should always use a high flashpoint oil. When using high flashpoint oils it's better to go for one formulated for 2stroke use since it will have less ash. Thermally challanged motors should use only very high flashpoint oil.

3. Carburator jetting:
Different oil have different viscosity and this affects carburator jetting and settings. This effect is more evident when switching between straight mineral and full synthetic. Normal people should use whatever type oil the manufacturer said. When dealing with really old outboards one has to experiment to find the right jets and settings (or pay someone to do it).

4. LPG (propane):
Any 2stroke motor with separate lubrification (Autolube and similar) can run on propane. The problem is normally finding a kit designed for small displacements and heating the gas. Bigger displacement engines are more easy to convert.

Thanks for the detailed and at least from my knowledge (admittedly limited) of the subject, accurate post.

[thinwater]

Originally Posted by skipmac

Thanks for the detailed and at least from my knowledge (admittedly limited) of the subject, accurate post.

I wouldn't call it accurate. Put your filters on.



1. Carbs only varnish if the gasoline is allowed to evaporate past a certain point before replenishing. I have never had to clean the carb in a car. I have never had to clean the carb of a boat motor if a quality anti-corrosion additive is used. It is also known that most "gumming" of carbs in the e10 age is the result of aluminum corrosion products forming gels that clog jets. They are not solvent-soluable, which explains why cleaning carbs has become more difficult. it is NOT that e10 makes tougher varnish, it is that it is not varnish at all.
2. Mineral oil contains zero ash. It is the extreme pressure additives added to PMC that cause that. Flash point and complete combustion are not related. Flash point is related to confined space explosion hazard of the vapor and is most related to the presence of a few low boilers. Fire point and dry point are the factors that relate to complete combustion. Perhaps this is just erroneous nomenclature. Mult-vis oil doesn't makes no sense in preblend oil, because the ONLY purpose is to stabilize viscosity over a range of temperatures to allow cold starting. That is obviously irrelevant, since the cylinders are hot and oil is dissolved in gasoline. What does matter is that multi-vis oils contain polymers that are very high evaporating.



Caster oil is actually a fat, not an oil, and thus has inherently superior extreme pressure properties. In fact, most metal rolling oils were palm oil or tallow based until the 80s. Many continue to be, although petroleum oils have gained market share.


3. I doubt there is a dinghy kicker out there, with stock tuning, that can tell what oil you are running. the effect of the oil on vis is miniscule. The difference in e10 vs standard mixture is FAR greater.


(I've been in refining most of my life.)


The thing about anecdotal reports ("this worked for me") is that a single report or even many are isolated data points, and they may have done even better doing something different. Does anyone actually believe that lube blenders spend real money on expensive additives that don't help? If you've ever been in any business you know that's not happening. They would claim they were in there and then not use them or add very little, but that is not the case. In fact, they add only what is needed.


In fact, small 2-stroke engines can smoke along on practically any oil for years, as is well proven in the 3rd world. I've read projects testing bio-diesel for this (higher ratio). I actually tried that on a 18hp outboard for 5 years, just to see. Worked fine, I guess (anecdotal stories are like that). But I would not recommend it.

[skipmac]

Well I reread the post from Rumpi and commented.

Originally Posted by thinwater

I wouldn't call it accurate. Put your filters on.



1. Carbs only varnish if the gasoline is allowed to evaporate past a certain point before replenishing. I have never had to clean the carb in a car. I have never had to clean the carb of a boat motor if a quality anti-corrosion additive is used. It is also known that most "gumming" of carbs in the e10 age is the result of aluminum corrosion products forming gels that clog jets. They are not solvent-soluable, which explains why cleaning carbs has become more difficult. it is NOT that e10 makes tougher varnish, it is that it is not varnish at all.


This is pretty much what he said IE varnish comes from evaporating gasoline. He did call it varnish. Perhaps not technically correct but a commonly used term.



2. Mineral oil contains zero ash.



I would say that would depend on how highly refined the oil is, whether mineral based or otherwise.



It is the extreme pressure additives added to PMC that cause that. Flash point and complete combustion are not related. Flash point is related to confined space explosion hazard of the vapor and is most related to the presence of a few low boilers. Fire point and dry point are the factors that relate to complete combustion. Perhaps this is just erroneous nomenclature. Mult-vis oil doesn't makes no sense in preblend oil, because the ONLY purpose is to stabilize viscosity over a range of temperatures to allow cold starting. That is obviously irrelevant, since the cylinders are hot and oil is dissolved in gasoline. What does matter is that multi-vis oils contain polymers that are very high evaporating.



Caster oil is actually a fat, not an oil, and thus has inherently superior extreme pressure properties. In fact, most metal rolling oils were palm oil or tallow based until the 80s. Many continue to be, although petroleum oils have gained market share.


3. I doubt there is a dinghy kicker out there, with stock tuning, that can tell what oil you are running. the effect of the oil on vis is miniscule. The difference in e10 vs standard mixture is FAR greater.


Vis = viscosity? No argument there. The difference in viscosity of the mix made with different types of oil would be negligible.



(I've been in refining most of my life.)


The thing about anecdotal reports ("this worked for me") is that a single report or even many are isolated data points, and they may have done even better doing something different. Does anyone actually believe that lube blenders spend real money on expensive additives that don't help? If you've ever been in any business you know that's not happening. They would claim they were in there and then not use them or add very little, but that is not the case. In fact, they add only what is needed.


Regarding additives, that has always been my belief but then would not the same apply to makers of two stroke oil?



In fact, small 2-stroke engines can smoke along on practically any oil for years, as is well proven in the 3rd world. I've read projects testing bio-diesel for this (higher ratio). I actually tried that on a 18hp outboard for 5 years, just to see. Worked fine, I guess (anecdotal stories are like that). But I would not recommend it.

From my very limited knowledge I cannot disagree at all with any of your points. My only point is, given the choice I will stick with recommended 2-stroke oil over other options. Might be fine to try whatever with a cheap, small kicker but with my 15 HP Yamaha that would be difficult to replace in the US where 2-strokes are banned, I'll stick with Yamaha oil. Considering how much I burn in a year it's cheap insurance.

[Rumpi]

1. I never said how long it takes to form varnish in a carburator, but yes it is not quick. It is more probable to have starting problems with stale gas then with varnish, but varnish is a possibility if given enough time. I also did not adress the E10 thing because I do not believe it to be relevant. I define varnish as the oxidized and/or polimerized residue left after evaporating. I have no other name for it altough I know it is not techically correct.

2. I never said oil contains ashes. That would be like sand inside the oil. I mean the (sulfated) ash formed after combustion of oil. Straight mineral oil (no additives) of the SAE30 type and other bearing oils used in 2strokes form them. Multigrade oils form even more ashes due to the additives (of wich most are not needed for 2stroke operation). On the other hand heavy duty multigrade diesel oil often has additives for better detergency or oxidative stability to minimize cylinder deposits. In practice this means that straight mineral oils tend to form hard brown/black deposits in the combustion chamber (wich is usually called coke) and some additivated motor oils form a more loose grey ashy residue that does not cement itself to the combustion chamber and piston top. In this regard they behave more like additivated 2stroke mineral oil.

3. The flash point is very important for 2stroke engines because this determines how the oil behaves on high temperature surfaces. Oils with low flashpoints also have lower dry points and are more likely to combust completley but that is not the issue. The issue is that an oil with a flashpoint of ~80°C simply does not have the same lubricating reserves as an oil with a flashpoint of ~200°C like most mineral oils have. Air cooled motors can not be thermally regulated so tightly as to use low flashpoint oils without any danger unlike water cooled motors. Tuning increases the thermal load outside designed parameters so racing oils all have flash points over 250°C.

4. Premix behaves differently from pure gasoline inside the carb and in how it burns. This has to do with oil viscosity and oil composition. If an engine is tuned so well as that the operator can feel the change between unleaded gasoline and E10 then he will feel the change from straight mineral to full synthetic.

5. A 2 stroke can be run on almost anything that lubricates and mixes with its fuel, but in order to achieve design life one should better use what the designer intended or know the compromises in doing otherwise.

[mikedefieslife]

If regular (and sometimes cheap) forecourt 2 stroke oils are leaving varnish and gumming up carbs left right and centre, then where are all the broken down scooters and mopeds in France, Italy, Spain etc...

[Compass790]

Originally Posted by John Engineer

Hi MarkSF.
In reality I agree as we all need to do our part to protect the environment so if the biodegradability of 2 stroke oil reduces harm to environment compared to any other oil that I say increases reliability it makes no difference.
2 strokes are filthy and you are right.
-------------
A different subject directly related to pollution from us is how we make electricity where we live and the car we drive. The carbon foot print we leave.
The diesel engines in our yachts with very inefficient propellers that turn far too fast and waste more than 50% of the mechanical energy available as an average.
This is not an to say MarkSF is wrong! Its to say he is right and the reliability of 2 stroke engines should be less important in our selfish lives.
I prefer to talk about how to make the world a better place to inherit after we are all gone!
Cheers John.

I've enjoyed your thread & found it interesting. Have used 15w-40 diesel oil in the past in the 2hp 2 stroke outboard because I've run out of 2stroke oil. Had no idea that they used to use SAE 30 before 2T specific oils. I wont sweat doing that now should we run out in a remote place given your real world examples. But yes I should help the environment & get a 4 stroke, it's on the plan. After all it's obviously unpleasant swimming in a 2 stroke slick.
thanks for posting

[Highlander40]

My experience shows that the alcohol in gas is much more dangerous.
Using pure gas produces quick starts every time, even the first start of the season.