# oil mix ratio for milling



## mikefunaro (Nov 21, 2008)

Sorry to bother you all with an oil mix thread, but I did a search and didn't find too too much. 

How rich do you go with your gas mix for milling? 40:1, 32:1??

MGF


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## Ironbark (Nov 21, 2008)

I run 40:1 synthetic. Read this thread for more advice:

www.arboristsite.com/showthread.php?t=53178&highlight=660+max+rpm+milling


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## BobL (Nov 21, 2008)

:agree2:


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## woodshop (Nov 21, 2008)

If you go over to the chainsaw section of this forum and do a search on mix ratio, you will have orders of magnitude more reading material on this subject than you will ever have time to read. If I recall, there is one thread on there from several years ago that runs hundreds of posts and gets pretty technical from both ends of the spectrum, both pro and con re: departing from the standard 50:1 ratio the manufacturers will tell you. Intersting post, but how many hours of that can you digest at a time ?

For what it's worth, and I happen to think this is quite an eye opener, when I bought my 395XP it came with the European version of the manual, and it stated that for their saws over 80cc to use 33:1 and not 50:1. (see pic below). Interesting. They don't make two different 395XP's... I bought this saw here in the US anyway... but the manual said 33:1 for their big bore saws. When I asked a Husky dealer about this he told me the saw won't pass govt emissions tests at 33:1, and that the big bore saws WILL run fine on 50:1. I find it interesting that Husqvarna is telling the Scandinavians to run 33:1 in their big saws, and the Americans to run 50:1. I run 36:1 in my 395 milling saw, and 43:1 in all my other saws. Been doing that for years, no problems.


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## Chickaloon (Nov 24, 2008)

*Milling oil ratios*

I am running 40:1 milling for several years in a Husky 395 XP and a Stihl MS660. But I got to say I can't imagine you would be doing something bad running 36:1. In fact I may just do that starting tomorrow !

Please don't run 50:1 and burn up your saw. I mean you could do that at 50:1 just holding your throttle open too long while log working. So if your milling, please increase your oil consumption.

Consider a ratio rite mixer.


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## mikefunaro (Nov 25, 2008)

Hey all--

thanks for your responses. 

I asked because I recently got a husqvarna 3120xp off of craigslist. I normally run my saws on 46:1 or so echo powerblend. I figure I'll make a special mix of 36:1 or so of Stihl synthetic for when I'm milling. 

Thanks for your help. 

MGF


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## mikefunaro (Nov 25, 2008)

woodshop said:


> If you go over to the chainsaw section of this forum and do a search on mix ratio, you will have orders of magnitude more reading material on this subject than you will ever have time to read. If I recall, there is one thread on there from several years ago that runs hundreds of posts and gets pretty technical from both ends of the spectrum, both pro and con re: departing from the standard 50:1 ratio the manufacturers will tell you. Intersting post, but how many hours of that can you digest at a time ?
> 
> For what it's worth, and I happen to think this is quite an eye opener, when I bought my 395XP it came with the European version of the manual, and it stated that for their saws over 80cc to use 33:1 and not 50:1. (see pic below). Interesting. They don't make two different 395XP's... I bought this saw here in the US anyway... but the manual said 33:1 for their big bore saws. When I asked a Husky dealer about this he told me the saw won't pass govt emissions tests at 33:1, and that the big bore saws WILL run fine on 50:1. I find it interesting that Husqvarna is telling the Scandinavians to run 33:1 in their big saws, and the Americans to run 50:1. I run 36:1 in my 395 milling saw, and 43:1 in all my other saws. Been doing that for years, no problems.




I noticed this in the manual and then called husqvarna. They tried to tell me to run 50:1 and disregard this manual, claiming it was a "typo". Clearly, however, the engineers made no mistake. 

MGF


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## Zodiac45 (Nov 25, 2008)

mikefunaro said:


> Hey all--
> 
> thanks for your responses.
> 
> ...



I wouldn't go that heavy with a modern saw Mike. I have a little 1 1/2 ounce chem beaker I use for a measure. 2 1/2 ounces is 50/1 and I just use 2 measures per gal. It works out too 42/1. I've run this mix in all my saws whether milling or felling, bucking or firewood. It's always been great. My neighbor and firewooding partner (RIP) blew up his Huskie 51 running his Homelite 360 and XL12 mix in it. His wife gave me the saw and when I pulled the jug, it had quite a carbon build up at the exhaust port. This carbon had flaked off and scored the piston and cyl and caused the ring too weld itself into the slot right there at the exhaust port. He was running 32/1. Just FYI but modern saws (with modern 2 stroke oil) I'd never go more than 40/1. I can see that allot of guys doing it but I'd say too pull your muffler ever so often and make sure she's not building carbon.


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## Chickaloon (Nov 25, 2008)

*Exhaust port piston scratches*

The last post has got me interested.

I would guess that this piston did not get damaged by carbon buildup....

Are you sure about this ?


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## woodshop (Nov 25, 2008)

mikefunaro said:


> I noticed this in the manual and then called husqvarna. They tried to tell me to run 50:1 and disregard this manual, claiming it was a "typo". Clearly, however, the engineers made no mistake.



...that is no typo, as if somebody accidentally inserted a 3 instead of a 5. When they wrote that manual they went to the trouble of making a two column mix oil chart, one column for their saws less than 80cc and one for their over 80cc saws. They state that for thier big bore saws run 3% oil, which comes out to be 33:1. This is not an old saw, it was bought 3 years ago, and the date on the back of the manual is (at least I'm assuming it is a date)...

2004-04-19

I'm quite sure the saw will run fine at 50:1, as many run even the big bores with that mix. However, there must have been a reason the Husky engineers originally recommended 33:1 for those larger saws... they didn't just do that on a whim. Again, I've been told by more than one dealer that the saws won't pass the US emissions test with that 3% mix. Not trying to start anything... I don't think there is some huge conspiracy where even though the slightly richer mix might be better for the saw in the long run, in order for them to pass emissions and be able to sell saws here they sacrificed longevity... don't necessarily think that's the case. Do I think that in the long run those big bore saws DO perhaps last longer with a richer mix? I'm not an engineer and can't tell you why, but yes.. I do think that. Thus if the manual that came with the saw says 3%, I'm gonna run with that and sleep like a baby.


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## FJH (Nov 25, 2008)

woodshop said:


> ...that is no typo, as if somebody accidentally inserted a 3 instead of a 5. When they wrote that manual they went to the trouble of making a two column mix oil chart, one column for their saws less than 80cc and one for their over 80cc saws. They state that for thier big bore saws run 3% oil, which comes out to be 33:1. This is not an old saw, it was bought 3 years ago, and the date on the back of the manual is (at least I'm assuming it is a date)...
> 
> 2004-04-19
> 
> I'm quite sure the saw will run fine at 50:1, as many run even the big bores with that mix. However, there must have been a reason the Husky engineers originally recommended 33:1 for those larger saws... they didn't just do that on a whim. Again, I've been told by more than one dealer that the saws won't pass the US emissions test with that 3% mix. Not trying to start anything... I don't think there is some huge conspiracy where even though the slightly richer mix might be better for the saw in the long run, in order for them to pass emissions and be able to sell saws here they sacrificed longevity... don't necessarily think that's the case. Do I think that in the long run those big bore saws DO perhaps last longer with a richer mix? I'm not an engineer and can't tell you why, but yes.. I do think that. Thus if the manual that came with the saw says 3%, I'm gonna run with that and sleep like a baby.



I don't beleive the engineers intended the saws to be used for milling!A richer mix is better for millng in my opinon I run a husky 2100 for a milling saw and when I work the saw hard ,even 2 ft into a big log the exhast is clean no smoke at all even at a 25 one mix Its getting hot enough to burn the oil totaly!I don't know how long it takes you guys to go thru a log but if your into a big log and its a 5 to 10 min run sometimes pulling full HP from the saw for 16 ft I want to be sure everything is well oiled.

Just another opinion!


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## BlueRider (Nov 26, 2008)

I think too much empasis is placed on what mix ratio and not enough on what oil is used. I wrote in another thread that I have been running 50:1 in a 1974 vintage 051 that is used exclusively for milling. The saw is equiped with a 42" bar runnng 404 chain. I have milled a lot of wood with this saw, I make furniture for a living and use only wood I mill. I very rarely mill anything under 24" and max out the bar more often than I can remember. I regularly mill logs that take more than one tank of gas per cut. Last year I switched to Stihl HP Ultra mix oil because it is a true low smoke oil. I am a bit lazy when it comes to mix oil and prefer to buy six packs of the little bottles that make 2.5 gal of mix. I have always used stihl oil except for the six pack just before switching to stihl HP ultra. My local stihl dealer refuses to stock any sthil oil products, he won't even order them for me. Guess where I don't shop anymore? I ran one six pack of Husky oil and it laid more carbon on the piston than 3x as much stihl oil. I know this because I regularly pull things apart to inspect and I actually pulled the piston and cleaned it so I could get an acurate idea of how good the HP Ultra oil is.

I have never tried amsoil but they recomend 100:1 mix for their 2 stroke oil in chainsaws. I would have a hard time being comfortable with that but I think the brand can have more impact than the actual ratio. I'm willing to be proved wrong so how about listing what oil you are running along with the mix ratio. and how about pics of pistons when things are pulled apart along with mix ratios and brands of oil. this seems like more of an end all to the my-ratio-is better-than-your-ratio-because... kind of threads than rehashing things over and over every few months.


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## FJH (Nov 26, 2008)

Rider!
You are correct.
I'm not an engineer or a scientist nor am I willing to pull the saw apart every few years to test a therory.But you are correct the type of oil for the saw can make a diffrence!I choose to use the cheaper generic oils And run a heavier mix than recomended, I'd rather be safe than sorry.I have had my saw seize up while milling due to trying to run with a loose carb (to lean fuel mix) this is by no means an oil mix problem but in my mind the oil I use is generic and I do not trust IT to do the proper job under such harsh conditions.So as you said the debate will rage on,With out testing several saws several times with diffrent oils under the same conditions it will always be a debate!
Just to many variables and not enough spare time to test the therorys! 
And also rehashing is FUN! Just like milling! 

Happy milling!


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## Brmorgan (Nov 26, 2008)

woodshop said:


> For what it's worth, and I happen to think this is quite an eye opener, when I bought my 395XP it came with the European version of the manual, and it stated that for their saws over 80cc to use 33:1 and not 50:1. (see pic below). Interesting. * They don't make two different 395XP's...* I bought this saw here in the US anyway... but the manual said 33:1 for their big bore saws. When I asked a Husky dealer about this he told me the saw won't pass govt emissions tests at 33:1, and that the big bore saws WILL run fine on 50:1. I find it interesting that Husqvarna is telling the Scandinavians to run 33:1 in their big saws, and the Americans to run 50:1. I run 36:1 in my 395 milling saw, and 43:1 in all my other saws. Been doing that for years, no problems.



Well, there is an EPA version sold now, and also a non-EPA version sold back when the model first came out, so maybe the Euros are still getting the non-EPA version? Don't know how/why that would affect the oil spec, but as you said 33:1 makes it tough to pass emission controls. Not that most of us care about that anyway. I usually stay between 32:1 and 40:1 for milling, and 40:1-50:1 for firewood jobs. I'm not too scientific about it, I have a 10L (a bit over 2.5 gal) gas can, so 50:1 is 200mL of oil, 40:1 is 250mL, 32:1 just under 300mL. I just eyeball it on the transparent measuring strip on the side of the 1 L Stihl oil container. Never burnt up a saw yet. Heck, my old Pioneer says 16:1 on the gas cap, though that was from the good old days when guys just grabbed some 10W-30 and mixed 'er up. Runs fine at 50:1 on the new stuff though.


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## Chickaloon (Nov 27, 2008)

*oil mix*

I am sure that most of the time it will all work out...

But a little insurance goes a long way...so a little richer is better insurance than the opposite.

And my saws run like a dream on 40:1 Stihl oil mix. Both milling and felling.

And to note....carbon buildup in the exhaust port will NOT score your cylinder....if you have carbon buildup and a scored cylinder you also have an AIR LEAK due to seals, lines or carb adjustment.


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## slabmaster (Nov 27, 2008)

It's good to add more oil to the mix when milling,however the carb should also be readjusted for the change.More oil means less gas in the mix.Less gas creates a lean mixture which can damage the saw as well.Always richen the carb setting when changing the mix ratio.


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## BobL (Nov 27, 2008)

slabmaster said:


> It's good to add more oil to the mix when milling,however the carb should also be readjusted for the change.More oil means less gas in the mix.Less gas creates a lean mixture which can damage the saw as well.Always richen the carb setting when changing the mix ratio.



I don't think this makes any difference unless you start operating at mix ratios below about 25:1

With 50:1 the gas represents 50/51'ths of the mix, or 98.03% is gas.
With 40:1 the gas represents 97.56% of the mix
I can't see a 0.53% difference in the amount of gas in the mix making much difference in terms of leaness. The critical factor in leaness is the "air to mix" ratio - not the oil to gas ratio. This has to change by 10's of percents or more to make a significant difference.

I agree that if the mix is changed significantly the carby should be retuned, to whatever the powerhead needs to run smoothly. Then for milling the high end should also be richened so that the machine RPMs a little lower than at smooth max.


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## Brmorgan (Nov 27, 2008)

BobL said:


> I don't think this makes any difference unless you start operating at mix ratios below about 25:1
> 
> With 50:1 the gas represents 50/51'ths of the mix, or 98.03% is gas.
> With 40:1 the gas represents 97.56% of the mix
> ...



:agree2: 

The whole problem with an engine running lean is that it doesn't get enough lubrication from the oil in the fuel. If you have a higher oil content, that will help mitigate the effects of running lean/hot to a degree. Still don't recommend it though. Too much oil will just cause a bit of power loss and some excess smoke and carbon buildup - I've never heard of someone blowing a saw up from overmixing.


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## Brushwacker (Nov 28, 2008)

Brmorgan said:


> :agree2:
> 
> The whole problem with an engine running lean is that it doesn't get enough lubrication from the oil in the fuel. If you have a higher oil content, that will help mitigate the effects of running lean/hot to a degree. Still don't recommend it though. Too much oil will just cause a bit of power loss and some excess smoke and carbon buildup - I've never heard of someone blowing a saw up from overmixing.



When an engine is run lean sure its getting less lubrication (less fuel oil mix flow in proportion to air)in a 2 cycle which = more friction from less lubrication which = more heat. But also more heat is produced because the higher oxygen burn verses the cooler fuel fire. The cutting torch flame being an example. Increase oxygen the flame burns hotter,increase propane the flame burns cooler.


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## Zodiac45 (Nov 30, 2008)

Brushwacker said:


> When an engine is run lean sure its getting less lubrication (less fuel oil mix flow in proportion to air)in a 2 cycle which = more friction from less lubrication which = more heat. But also more heat is produced because the higher oxygen burn verses the cooler fuel fire. The cutting torch flame being an example. Increase oxygen the flame burns hotter,increase propane the flame burns cooler.



That's right.:agree2:


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## chopperlot (Dec 5, 2008)

HAVE BEEN USING A HUSKY 395XP FOR MILLING FOR 3.5 YEARS USING A 46" BAR AND MILLING HARDWOOD (IRONBARK) I RUN 25:1 MIX NEVER HAVE A PROB. :greenchainsaw:


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## Chickaloon (Dec 7, 2008)

I think the argument that the saw is running leaner is accurate if all you care about is gas to air ratio, but when there is oil substituted for gas and it runs through your cylinder, then the lubrication factor is quite high.

You should only have to adjust your carb if you are running LESS than 30:1

So as long as you mix rich with oil and keep your carb setting at the standard 50:1, then you will not be in danger of overheating your saw.

This has become an interesting thread I must say


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## John Bartley (Dec 14, 2008)

Chickaloon said:


> And to note....carbon buildup in the exhaust port will NOT score your cylinder....if you have carbon buildup and a scored cylinder you also have an AIR LEAK due to seals, lines or carb adjustment.



Ummm ... not quite true....

It's true that the built up carbon will not score your piston or cylinder as long as it stays where it builds up.

However...

The problem occurs (and I have seen it many times in my years as a saw dealer) when a chunk of built up carbon breaks away and get trapped between the piston and cylinder. The scoring from the trapped carbon can be identified when the scoring happens in a place that wouldn't normally be identified with lean air/fuel mixture failure, and when a pressure/vac test reveals no leaks. Troubleshooting and failure analysis will always tell the true story.

As regards richening the fuel/oil mix for milling, my preference would be to richen the fuel/air mix (not the fuel/oil) so that the saw runs a bit cooler and let the oil work in its correct temperature range.

cheers

John


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## slabmaster (Dec 15, 2008)

John Bartley said:


> Ummm ... not quite true....
> 
> It's true that the built up carbon will not score your piston or cylinder as long as it stays where it builds up.
> 
> ...



+1 I agree on both counts! Carbon is harder than aluminum and can surely damage a piston in a saw fast.As for the fuel, as i said earlier when you richen your oil to the mix, the carb has to also be adjusted for the change as well.Even a 4 stroke will burn up when run lean when it's getting all the oil it can from the oil pump.The extra oil doesn't help the saw when it's getting to little gas to the air mixture no matter how much oil is in the mix.And by adding more oil to the mix,you are feeding less gas to the saww which can cause it to run too lean.I have a motec degree in small engine repair, so it think i know what i'm talking about here.


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## BobL (Dec 15, 2008)

slabmaster said:


> And by adding more oil to the mix,you are feeding less gas to the saww which can cause it to run too lean.I have a motec degree in small engine repair, so it think i know what i'm talking about here.



Most small engines designed to last for some time are made with a range of operating tolerances. It's true that if you are operating right on the border of leaness with a saw, a very small additional increase in the amount of air can cause damage but let's assume the saw is operating in the middle of the range so it can tolerate some changes in leaness. The question is how much can it tolerate.

Lets say one day a saw is tuned with the air pressure at 1000 mb and the next day the air pressure increases to 1020 mb. Should the saw be retuned?

1000 to 1020 mb is not a big variation, but it represents 2% change in air pressure. That means the saw will get ~2% more oxygen than when the saw was first tuned.

Changing the mix from 50:1 to 40:1 will result in only a 0.5% difference in air to gas ratio - so the normal change in air pressure will cause a greater variation in leaness than changing the mix from 50:1 to 40:1

Atmospheric pressure at sea level can vary by +/- 2%, from around 990 to 1030 mb, or over a 4% range. To make a 4% "air to gas ratio" the "mix ratio" will have to be changed from 50:1 to 16:1. This air pressure increase is about the same as dropping from 1000 ft above sea level to sea level. Except for a guy that raced saws, I don't know of anyone that successfully operates saws and retunes for this 1000 ft difference.

To provide another indication of when saws should be retuned when dropping from altitude to sea level, lets look at the following, dropping from 2000 ft represents a 7% difference in air pressure, 4000 ft a 13% difference, and 6000 ft a 19% difference. Where I live pretty well all our forests are below 2000 ft and I do not know of any faller that retunes for altitude so it seems than that saws can readily tolerate this 2000 ft or 7% difference. Bear in mind I'm not saying that saws would not benefit from a retune, its just that I don't see fallers doing it and I don't see their saws being damaged. Anyway, the 2000 ft difference is equivalent of a mix ratio change from 50:1 to 11:1. 

As others have said, well before then, a more significant problem of dropping the mix ratio will be carbon buildup due to too much oil.


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## slabmaster (Dec 15, 2008)

Air pressure and volume are two different things Bob.The carb has to be readjusted for volume not air pressure, so that's why you don't see the fallers readjust for altitude.When you put more oil in the mix, you're changing the fuel volume not pressure.:monkey: Add ethonal in the mix and you have a real concern today when running lean in a chainsaw.More so when milling!


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## BobL (Dec 15, 2008)

slabmaster said:


> Air pressure and volume are two different things Bob.The carb has to be readjusted for volume not air pressure, so that's why you don't see the fallers readjust for altitude.When you put more oil in the mix, you're changing the fuel volume not pressure.:monkey: Add ethonal in the mix and you have a real concern today when running lean in a chainsaw.More so when milling!



Humm . . . . I can see you have not really understood what I have posting. The pressure and volume are indeed confusing. Let's stick to molecules since they are more concrete.

The amount of heat or energy from each firing of the plug depends on the number of molecules of air, and the number of molecules of gas (fuel) inside the cylinder. The number of molecules of gas is more or less fixed by the carby jet but the atmospheric air pressure will affect the number of molecules of air getting inside the cylinder. That is why is a saw tuned for 6000 ft above sea should be retuned when operating at sea level. Otherwise the saw will take in too much air and run too lean. It is even recommended that some saws are re-jetted for large differences in elevation.

The reality is that the variation is ambient air pressure regularly changes the degree of leaness by about 2 % and most saws cope with this quite well. Changing the gas-oil mix from 50:1 to 40:1 changes the number of molecules of gas relative to the number of molecules of air by only about 0.5%


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## slabmaster (Dec 16, 2008)

What i am saying is anytime the air fuel mixture has been changed weather it from altitude or less gas in the mix, the carb should be adjusted for the change as well.I always make sure the saw is running slightly in the rough at high speed after any change in the fuel mixture.I have noticed the rpms change when going from 50/1 to 40/1.so that says something about readjusting the carb when changing the mix.Better to be safe than sorry.


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## BobL (Dec 16, 2008)

slabmaster said:


> Better to be safe than sorry.



Yep - I can definitely agree with that.


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## DMax441/241 (Feb 20, 2017)

Brmorgan said:


> :agree2:
> 
> The whole problem with an engine running lean is that it doesn't get enough lubrication from the oil in the fuel. If you have a higher oil content, that will help mitigate the effects of running lean/hot to a degree. Still don't recommend it though. Too much oil will just cause a bit of power loss and some excess smoke and carbon buildup - I've never heard of someone blowing a saw up from overmixing.


More oil = lower octane also which in turn creates more heat


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