50:1 or 32:1 mixture

[Dagger]

Let me Mention a couple a things from an engine developers view...
first..the wrongs...
NO the 50:1 was not forced upon us by EPA regs!
HEAT WAS THE CULPRIT..
JEEZ,... and air-cooled 2 stroke saw engine is NOT really aircooled..75 to 80 %of the cooling is effected by the fuel,,the remainder by air.
As we were struggling to get our RPMs up higher than the other guy..but still having to give a warranty as demanded by the sales dept, alot of things came in to consideration..
keep down the heat...a cooler engine last longer!
FACT: GAS cools BETTER than oil
FACT: GAS burns better and cleaner than oil (no , we didnt care about smoke)it was unburned deposits in the combustion chamber, ending up in the ring grooves and on the piston walls causing siezures...and oh man..we had alot a that in the early days
we found nika-sil helped keep the heat that was building up in the walls from transferring to the piston...which we could keep cool by the fuel on BOTH sides of better than we could keep the jug cool. (*** below)..( no , it wasnt to make the bore slicker!)

FACT: the design CLEARANCE TOLERANCES and rpm level and side load factor dictate how much oil is needed..tighter tolerances...LESS OIL FILM THICKNESS..meaning less required in the ratio..we can caculate a volume requirement from this...
in other words % air/fuel (about 28 to one for highest cylinder pressure) X CFM's( that engine is just an air pump right?)
convert that to a volumetric measurement of your choice and we know how much fuel we have going thru the engine...now.in that much fuel, we put in the amount of oil need for lubrication..as dictated by above criteria..add a certain safety factor..(industry standard of 1.25 to 1.5 ) to help us get thru the warranty period whilst all them "EXPERTS" were fooling with the carb adjustments to make em run faster.
that is how manufacturers determine the recommended ratio
NOW..convince the public that MORE is NOT BETTER!
we have been trying to do that for years!
RULE..
a leaner oil mix ratio has better cooling properties than a heavier ratio. DUE to higher volatility (evaporative properities) of gas than oil.
unburned oil looks like varnish and gets "painted" on the piston skirt/sides..this in effect makes the piston "bigger" in the bore and decreases the thickness of the oil film.
This will lead to premature failure..

Why would a manufacturer, who must guarantee his equipment, recommend anything other than the absoulte BEST ratio for it?
Why would a manufacturer spend countless dollars on service schools for their dealers trying to explain just why a higher ratio/MORE oil is bad?

Some a you guys give me bad dreams!

 

[bwalker]

Dagger, First thing I want to say to you is that I respect the fact that you where in the biz and are a engineer, but I disagree with some of your points.

NO the 50:1 was not forced upon us by EPA regs!

No, maybe not by legislation, butThe mfgs relised that if the where to clean up there image and score some brownie points with the EPA the would have to elimnate smoke. Hence the drive for low smoke oils and reduced ratios.

FACT: GAS cools BETTER than oil

May be, But the differance between 50:! and 32:1 interms of the actual amount of oil in the combustion chamber is minimal dont you agree? Secondly does gas really cool a motor more? It might, it might not. Compare the heat of vaporisation of the two. Oil is considerably higher so would in fact it not leach more heat out of the combustion chamber? I know you will say there is a btu differance and there is, but will it make up for the higher vaporization rate of the mix oil?

was unburned deposits in the combustion chamber, ending up in the ring grooves and on the piston walls causing siezures...and oh man..we had alot a that in the early days

I dont doubt it, but oil tech has come a long ways since you where in the biz. Low ash dispersant technology has cured the carbon/ stuck ring problem you speak of. Todays pump fuel stinks so bad most deposits you see in two cycle running quality oil are from the gas itself. Pump fuel runs back to back throught the same pipelines as diesel and a plethora of other products so mixing can and does happen which leads to deposits in a two cycle.

we found nika-sil helped keep the heat that was building up in the walls from transferring to the piston...which we could keep cool by the fuel on BOTH sides of

Nicasil was also used because chrome cylinders reach a rpm point where oil will no longer adhere to the cylinder wall which causes galling. Also, In a two stroke the main problem is keeping the piston cool, not the cylinder. Since it is exposed to the combustion event once per revolution it builds and holds much more heat than a four cycle. The piston transfers this heat to the heat sink(cylinder) where airflow from the fan and radiant heat dispersion get rid of it.

FACT: the design CLEARANCE TOLERANCES and rpm level and side load factor dictate how much oil is needed..tighter tolerances...LESS OIL FILM THICKNESS..meaning less required in the ratio..we can caculate a volume

Its pretty comon knowledge that tighter clearances do require less viscosity, but not less oil volume. I think you will find todays oils have lower viscositys to address this concern.

a leaner oil mix ratio has better cooling properties than a heavier ratio. DUE to higher volatility (evaporative properities) of gas than oil.

IMO thats abit speculative with the points I have mentioned above. Gasoline does evaporate at a lower tem, but which will leach more heat out of the combustion chamber? the btus to evaporate oil will certainly be higher than that for gas will they not?

unburned oil looks like varnish and gets "painted" on the piston skirt/sides..this in effect makes the piston "bigger" in the bore and decreases the thickness of the oil film.

This is only a problem with low tech oil. Add to that the MFGs insisatnce on peddaling low grade dyno oils at a high cost point for them and the fact that EPA mandated mufflers make piston temps go sky high. Its no wonder there is a varniosh problem. The oils is simply coking in response to being subjected to to much heat.

Why would a manufacturer, who must guarantee his equipment, recommend anything other than the absoulte BEST ratio for it?

Two words. The EPA and CARB. The auto MFGs do the same thing. They reccomend a 5w20 weight oil for Fords new f series trucks this year. The motor hasnt changed in the slightest and is the same one the reccomended a 10w30 a few years ago, but the could gain a bit in cafe so they did it. At the expense of the consumer.
There are also many SAE papers that relate the fact the "more is bettter" better when it comes to oil in a two stroke motor. BTW I know my wrighting and spelling stink, dont rub it in.

 

[Dagger]

Walker, thank you for your kind words in the begining of your post. and as for the end of you post...I sure wont rub it in..I think you spell better than I do! Plus...the way you have figgered out how to do those lines and quotes makes me jealous...it makes a discussion much easier to run. I gotta figger that out.

Let me expand on my viewpoint. If you walk over here on my side a the creek...the water looks a little different.

In the early 80's the market was heavily influenced by advertising warranty...most consumers seem to think that if you warranty a product longer than the other guys..it must be better.
Actually it is a function of sales...not reliability
so, the sales dept wants a long warranty period to enhance this image.
This herein is where it all started. it was not the EPA...they had no jurisdiction on our market then, and we did not consider them fer a sec. That came several years later...after most had switched to 50 to 1 oil already.
When they did start regulating our industry..it was the oil companies that faced the burden of developing low ash oils..low smoke..as so on...not any of the equipment manufacturers.
We tried then to purchase a better grade of oil for our brand labled bottles...but in fact could not. what we encountered was my first expierience in trying to buck the oil company monopolies.
Distributers in the midwest had to buy oil from a refinery/bottler in the midwest...east coast distributors had to buy from the east, and west coast were prevented from ordering from any other place than the west...anyway,,,thats for a different thread.
Now..back in Sweden, engineering was faced with the task of keeping warranties down to an acceptable level with an extended term offered. This was the task we were assigned.
I promise you, I was there.

Now, as you correctly mentioned. Volume /viscosity of oil must be considered.
also what must be considerd is the oil in the fuel mixture does not burn at the same rate as the gas..and when the volume is increased..so is the unburned oil, these are the deposits i speak of..unburned oil..not coke, or carbon,or other hard crispy stuff cause you are right..alot of that comes from crap in the gas. BUt they do not contribute to skirt "painting".
as you mention, the difference is not very much when you figure the volume of oil in 1 charge of the cylinder fuel mix...but what happens is a little oil is left in the combustion chamber unburned...and compound that with rpms and time...and it quickly builds up. conversely , a lower oil volume builds up much less quickly, so , with extra oil and the resultant cooking of this oil on the hot piston( also as you mentioned, the piston is the real hot surface in there) and begins to build up on the piston walls...usually right below the rings...many of you have seen this varnish looking brown "painted" on the piston below the rings on the piston. Anyway you look at it..this is from more oil than the engine can burn..discharge..or generally cope with in the fuel mix.
this layer displaced the oil film between the piston an cylinder..and hence...leads to early failure.
Remember...this was in a time when we were all bringing our saws up to the 12000rpm and above level, and had to have less skirt/wall clearance than in the previous models. so we had to deal with less cushion anyhow...to get our saws to meet an acceptable level of warranty in the now longer term offered, we needed to figure out how to reduce this buildup.
we accomplished it by using bearings from SKF that required less oil...nikasil cylinder coatings that were porus enough to keep the oil film in place at a closer tolerance, and reducing the oil in the fuel mixture.
This recipie didnt just come real easy...several cylinder coatings were tried...lots of bearing designs...and it was the Italians that came up with the nikasil and when they presented us with sample cylinders to use, we could finally see the light at the end of the tunnel. for a time, you could only buy Nikasil coated cylinders from them, and they soon were supplying cylinders to anyone who wanted to go over 12000 rpms ...I wont go further there...could start another whole thread!

lastly...on that point you mentioned about trying to score points with the EPA....
even tho that consideration came several years later...No one I know even tries...EPA is considered a blind elephant...and scoring point with them is thought of like building a step ladder to the moon, cant be done, so aint even tried.
We wait..see what dumb idea/regulation they implement, and consider it a challenge to try and make a marketable product that will comply.


So, thats kinda what the water looks like from this side. I was right there bout knee deep in the creek when we were workin on problems and solutions. I know I wasnt told everything..just a young engineer given a task. but we never were told to meet any emission requirements...or make it run cleaner for the sake of the exhaust. Not then....that came several years later. and i was still there....then we worked on that.but not very hard. The carb regs that gave us most problems were NOX requirements...and what ever oil we used did not really matter much there..we needed to burn less gasoline.....now, talk about a problem...make more power and do it with less gasoline....whew...thats where we still are!

 

[Crofter]

Gas to oill ratio versus fuel to air ratio

Would the boys who support a richer oil to fuel ratio be trying to compensate for running their saws with a marginally lean fuel/air ratio? In this condition which would be more likely to contribute to seizure; the higher temperature caused by the lean mixture or the reduction of piston clearance caused by buildup of varnish on the piston from the extra oil?

Just wondering,

 

[bwalker]

We tried then to purchase a better grade of oil for our brand labled bottles...but in fact could not. what we encountered was my first expierience in trying to buck the oil company monopolies.

I would love to hear that story.

Dagger, Today the "painting" of the piston is not a probelm with ISO EGD oils. The unburned oil in the chamber you mentioned is because back in the 80's when you where in the biz two stroke oils relied on something called brightstock to reduce piston scuffing and wear.Bright stock is basicaly a very high viscosity petroleum oil that is almost tar like in nature. It allowed the oil co's to get away with peddeling a cheap product because it required very little additizes to reach exceptable scuff prevention. The problem is the fire point of bright stock is very high so its doesnt burn to well. It tends to oxidize and form nasty deposits as well as "paint" the skirt as you mentioned. Todays oem oils like orange bottle stihl are comprised of brightstock, a solvent to aid in mixing, a very small amount of low ash dispersant(calcium based), and some fuel stabaliser. ISO egd oil on the other hand usually have a synthetic base or very highly refined mineral oil bas mixed with a synthetic componenet calles poly iso butene. added to either of these bases is a additive package comprised of dispersant, anti scuff additves. The additve package of a iso oil may be as high as 35% of the total product. Compared to the 5-15% of the oem mix oils it is easy to say why ther burn much cleaner. In conclusion oils that meet the iso spec will burn cleaner at 32:! than the oem oils would at 50:1. The problems you ran into in the 80's have been solved by new technology. BTW nicasil is a patented process developed by Mahle, a German co. The term nicasil is used pretty loosely as there are many types of nickel matrix coatings available. I wonder what type is in the cylinders found in saws?

 

[tundraotto]

Originally posted by Dagger
it was not the EPA...they had no jurisdiction on our market then, and we did not consider them fer a sec. That came several years later...after most had switched to 50 to 1 oil already.

then the EPA made the 50:1 ratio not work so well with the new plugged up EPA compliant mufflers?

 

[bwalker]

Would the boys who support a richer oil to fuel ratio be trying to compensate for running their saws with a marginally lean fuel/air ratio? [/QUOTE
No. Compensate for what?

In this condition which would be more likely to contribute to seizure; the higher temperature caused by the lean mixture or the reduction of piston clearance caused by buildup of varnish on the piston from the extra oil?

MORE OIL DOES NOT LEAD TO VARNISH. CRAP OIL DOES.

 

[Dagger]

Walker, Right ,,bright stock looks like STP..in fact, STP used to be about the highest brightstock content stuff a fella could get off the shelf. And you describe its characteristics perfectly
I have also always believed that synthetic oils would be better than a petroleum bright stock lubricant. I dont know enuf about them to know one from the other, but I have no doubt that the burn away could be made to be better and surely there are some that work very well.
ISO EGD...??? I dont know that spec, are there any examples of this spec labled by a chainsaw company ?
I would like to try some however...can you recommend a brand?

Alas..Then is still now..... I reckon the reason we see the problem still today just like we saw it then, is because of the dealers practice to try and sell the company labed oil, and none use it.
believe we can agree that the practice of mixing a company branded oil,,,at.al..sthil, husky,Solo..echo, what ever..at a higher ratio than 50 to one is a bad practice in todays leading saws.
Synthetics however, a different story.

Walker, you bring great discussion here. I think you outta be on that moderator poll!

 

[tundraotto]

Originally posted by Dagger

ISO EGD...??? I dont know that spec, are there any examples of this spec labled by a chainsaw company ?
I would like to try some however...can you recommend a brand?

the standard is actually ISO-L-EGD. JASO FC is another one to look at, its the highest Japanese standard for 2 stroke oils, and I believe that it is even more stringent than the ISO-L-EGD (I may be wrong but ben will find out, LOL). No bad oils exist within oils comlying with these standards for 2-stroke oils. Examples are: husky, echo, and stihl oil.

You can always go better with a synthetic such as Mobil MX2T or MOTUL 800 2T.

 

[don]

Moyul 800T

In another discussion very similar to this I switched to Motul 8002T synthetic based on the Walker's convincing point of view.
Very happy with this discussion.

For a big saw like 066 it seems to handle better under long stress running a 36 bar. Just doesn't get as hot as it used to and no smoke.

Found a place in California selling it for $under $40 a gallon delivered. So I go from Stihl black label for $30 a gallon to this for less than a 10 dollar difference.

No exhaust smell and smells like bazooka bubble gum prior to the mix.

Maybe it smells like original flavored Bubble Yum Bubble gum.

Do you think we should discuss, maybe a poll for our favorite exhaust smells?

 

[bwalker]

ISO EGD...??? I dont know that spec, are there any examples of this spec labled by a chainsaw company ?

Stihl black bottle, echo premium are two oem examples. Mobil MX2T available at autozone for 3.50 a pint is my favorite.

the standard is actually ISO-L-EGD. JASO FC is another one to look at, its the highest Japanese standard for 2 stroke oils, and I believe that it is even more stringent than the ISO-L-EGD

The jaso FC standard has less strict deposit control and scuff tests than the iso-l-egd as it directed to smoke control more than anything else. Iso egd does use the jaso fc smoke test as part of its standard. Overall the iso standard is much harder to pass. Iso egd oils must be part synthetic at the minimum to pass while some dino oils still pass jaso fc.
Otto for the price mx2t is very hard to beat although Motul 800 will take abit more heat. It cost alot more also. Don really got a great price on it.

 

[tundraotto]

Originally posted by bwalker
Iso egd oils must be part synthetic at the minimum to pass while some dino oils still pass jaso fc.

I knew that no dino oils passed the ISO-L-EGD, but didnt think any of them passed JASO FC either, which dino oils pass JASO FC?

btw. got a gallon of Motul 800 on the way to try out.

 

[bwalker]

Otto, of hand I cant remember. I could do some digging and find out.

 

[don]

Motul 800T

btw. got a gallon of Motul 800 on the way to try out.

What did you pay ?

 

[tundraotto]

$29.95 + $13 shipping - from cycle tech who you recommended. I could not find it cheaper anywhere.

 

[bwalker]

Thats really cheap Otto. It sells for around $15 a quart in my area.

 

[don]

Great to know

I couldn't find it for less. I even called Motul and obtained a couple West coast distributors and was quoted around $35 and had to buy $500 worth of it.

I guess allot of the guys at Ctech ride / race with Motul people out in the desert. The motul guys didn't refer me to Ctech. The two facilities are less than a hour away from each other.

Hey I'm not gonna complain ... the distributors wouldn't be too happy about it ... and I'm not tellin.

Does synthetic have a shelf life?

What is an appropriate shelf life for a fuel mix?

How does stabilizer work? Is it worth while?

Thanks all.

 

[tundraotto]

Re: Great to know

Originally posted by don
Does synthetic have a shelf life?

What is an appropriate shelf life for a fuel mix?

How does stabilizer work? Is it worth while?

Thanks all.

Yeah that was a good deal (800T) - I should get it sometime next week and will try it out. Hope it smells good or has no smell like MX2T...LOL

synthetic shelf life? - I dont think so if it has not been opened (several years I imagine) - if its open I dont know
shelf life for mix - I dont keep mine for over 4weeks
stabilizer - a must for all 2 cycle equipment unless you burn all your gas in a week or so. It prolongs the fuel degradation process - it does not eliminate it. It does work though.

 

[bwalker]

Provided the container is sealed it will last for years. If it has been opened and is sealed tightly you shoud not have a problem if you use it within a few months. Motul 800 is ester based so it will draw moisture out of the air if the container is not sealed tightly. As far as mixed gas going bad. If you store it in a steel can it will last a very long time. When stored in plastic it begins to degrade rather soon, so I always use steel cans. Its best to only mix up the amount you will use in a weeks time.
Otto, Motul 800 has a very slight smell which is better than mx2t IMO. It smells kind of sweet.

 

[Greg Carberry]

Walker you seem to know your stuff well. Very good thread so I will ask you a few questions.

What is better castor or full synth?

Is Klotz oil any good the BC-175 castor or and the R50 full synth? Alot of guys run Klotz around here for racing and swear by it.