40:1 instead of 50:1?

[Todd]

I read on the topic of over-revving that some forum members were reccomending using a greater amount of oil in their pre-mix than the saw reccomends...using only 40:1 would let me keep just one can of mix around for my 2-stroke toys, but will my 394xp like getting the extra lube(50:1 reccomended), and what adjustments should I then make to the carb?  (or should I find someone who knows what the h*** they're doing to adjust it?  
Todd

[clyde]

Your saw will be much better off at 40 to 1.  I think 50 to 1 is too little oil.  You really shouldn't have to tune it much with this change.  Theoreticaly it will be a little leaner on the fuel to oxygen ratio (less gas and more oil in a given volume) but this will be very slight.

[Rocky_J]

http://www.madsens1.com/sawtune.htm

[scottr]

Todd , about a month ago a similar question on another forum revealed that Husqvarna recomends 3% oil for their saws that are over 80cc .

[Rockn H]

So, husqvarna recommends around a 33:1 mix?

[KarlP]

So, husqvarna recommends around a 33:1 mix?

I used their online form to ask them about this twice and got no response.  The third time I asked a simpler question to start with and followed up with what I really wanted to know.

Me: "What fuel to oil mix ratio to you recommend for the longest engine life of a Husqvarna 385xp used for chainsaw milling?"

Husq: "Thank you for contacting Husqvarna. The best fuel/oil mix will be the 50:1 ratio using quality 2 cycle oil that is designed for chainsaws, and use fresh fuel, 89-93 octane for best performance."

Me: "In that case I'm curious if you could tell me why one version of the US 385xp manuals (http://weborder.husqvarna.com/order_static/doc/HOUS/HOUS2004/HOUS2004_1140238-95.pdf) as well as all of the manuals for New Zealand, Sweden, and many other countries recommend 33:1 for Husqvarna saws over 80cc? I assumed it was for longer engine life."

Husq: "The different ratio can be attributed to different fuel quality in the countries that you listed. The owners manuals for all Husqvarna products in the US call for a 50:1 fuel ratio."

That said, I myself use a 1 gallon Husqvarna mix in .85 gallons of Super Unleaded from the local Exxon station that has one hose for each grade in a new saw just incase the rumors of conventional oil leading to a better breakin are true.  After that I switch to 3oz of Mobil 1 racing per US gallon.  That both makes measurement easy and gives me around 42 2/3:1.

[Rocky_J]

The other countries do not have the EPA. No manufacturer is legally allowed to recommend anything more than 50-1 mix in the USA. The other countries are not restricted by such legalities and they can actually recommend the mix that the saw was designed to use.

[scottr]

 I just looked up the fuel to oil ratio for the new model PP4318AV that Stew was asking about . The ratio is 40:1 .

[Ianab]

Interesting...

I picked up a new Dolmar 9600 last week.
The (International) user manual tell me to mix the oil 50:1. But the dealer AND the free ( bottled in NZ ) Dolmar oil bottle both say to mix 25:1

I'll just carry on mixing 33:1 like I do with all my 2 strokes, none have died yet 

Husq: "The different ratio can be attributed to different fuel quality in the countries that you listed.

I have been told that by various dealers in NZ too, and I can believe it as well 

Ian

[StihlDoc]

The other countries do not have the EPA. No manufacturer is legally allowed to recommend anything more than 50-1 mix in the USA. The other countries are not restricted by such legalities and they can actually recommend the mix that the saw was designed to use.

To clear up any misconceptions, the EPA does not mandate any mix ratio on two-strokes. The manufacturers tell the EPA what ratio and oil formulation is used when they give their emissions level data to the government. The ingredients in the oil and engine design are the determining factors in what a manufacturer recommends for a mix ratio.

[bitternut]

So if I were to read between the lines the saw manufacturers stroke the test results by using a 50 to 1 mix but really design the saws to run best on a richer mixture. Since there is no EPA outside the US they are free to make recommendations of a richer mix.

[Joseph]

So if I were to read between the lines the saw manufacturers stroke the test results by using a 50 to 1 mix but really design the saws to run best on a richer mixture. Since there is no EPA outside the US they are free to make recommendations of a richer mix.

Look like that, does it not?

I did look up the Operator's Manual{International Version] for my saw, a 395XP.

I will be running my saw on 33:1{3%] mix, per there International Operators Manual.

You can see a copy here;
http://weborder.husqvarna.com/order_static/doc/HOEN/HOEN2004/HOEN2004_1140256-26.pdf

And Yes they have the following on page 25, bottom right;

Mixing ratio
For engines up to 80 cc: 01:50 (2%)
For engines over 80 cc: 01:33 (3%)


Regards

Joseph

[Todd]

I just wanted to thank everyone for their responses...I think I'll start mixing a little more oil into that premix and quit worrying about getting that "exact" mixture now that I hear others are running 40-33:1 in their saws.  Watching me trying to get EXACTLY a 50:1 mix would probably have been an amusing experience for most people here. (and no, before anyone asks, I don't have any pictures of that! )
Todd

[StihlDoc]

So if I were to read between the lines the saw manufacturers stroke the test results by using a 50 to 1 mix but really design the saws to run best on a richer mixture. Since there is no EPA outside the US they are free to make recommendations of a richer mix.

The oil mix ratio has only a minimal effect on what the EPA regulates. Scavenging loss (unburned gasoline) is the big contributor. The 50:1 ratios are recommended because the modern two-stroke oils have better additives to prevent ring sticking and piston seizure than the oils used 20 years ago. The newer oils used at richer than ecommended ratios can lead to deposit build-up and eventual engine damage over the long term due to deposit build-up.

[sawguy21]

I am with StihlDoc on this one. Running a richer mixture also leads to plugging the ports and spark arrestor. I have not seen any oil related problems at 50:1, I have run my Husky 345 at 100:1 on Opti-2 for the last 5 years. However, it is your saw and your nickel, if you feel better running heavier by all means go for it.

[JD_Kid]

Hi ya's
Ianab intresting what ya say about  ya new saw  my  109 is ment to be 40-1 my 120Si  is 25-1 and my PS 9010 40-1  or higher if useing "brand oil's"   i have run all these on 100 -1 race oils tho   i think a lot depends on oil spec than mix rates
catch ya
JD

[bwalker]

The newer oils used at richer than ecommended ratios can lead to deposit build-up and eventual engine damage over the long term due to deposit build-up.

With all due respect, i know this is the Stihl company line. Its complete BS. OIl technology has changed very little untill the last 5 or so years. Well after 50:1  ratios first begain to be reccomended. the OEMS went to the numercily higher ratios in order to reduce visible smoke with the mediocre quality oils they sell.
 I run all my saws at 32:1 and I would challenge you to see anymore smoke than stihl orange bottle oil at 50:1 In fact I will bet you my saw will smoke less. Further more deposit levels will be less.

[Tillaway]

If you ever have a chance to look through Stihl's engine failure diagnostic manual you will find that running a mixture too rich say 33:1 leads to excessive carbon build up and piston scoring on the exhaust port side and ring sticking as the carbon build up falls back in on the piston.  It is the equivelent of running too lean as far as engine failure.  Probably more common since most people are more comfortable running a rich mix since they feel better.  Most folks don't notice the reduced service life since they put very few hours on a saw so service life still appears to be good to them.

Outboard manufacturers have had to deal with this problem for years since the fuel / oil mixture is rated to protect at wide open throttle.  They rarely run WTO all day so trolling was extremely hard on them and the motors suffered greatly as well as pumped allot of unburned oil into the water.

[sawguy21]

Tillaway is absolutely correct. With all due respect to bwalker and others, oil technology has changed dramatically and so have engines. The old engines had wider tolerances so required more of the oil that was available at the time. They also ran at lower speeds and did not need the new super oils.
 A friend who is from the old school insisted on running his Johnson outboard on SAE30 at 16:1 just as he did in the fifties. I convinced him to use outboard motor oil because of hard starting and fouled plugs. He still refuses to go any leaner than 20:1 yet there is a white goop which is water and unburned oil in the exhaust port. The new concentrated oils simply will not burn clean when mixed too heavily.

[StihlDoc]

With all due respect, i know this is the Stihl company line. Its complete BS. OIl technology has changed very little untill the last 5 or so years. Well after 50:1  ratios first begain to be reccomended. the OEMS went to the numercily higher ratios in order to reduce visible smoke with the mediocre quality oils they sell...

With all due respect, I have been around two-stroke engine and lubricant development for over 30 years and have not experienced the same observations you supplied. I would be interested to know where your information comes from or is it personal opinion?

[clyde]

I don't believe , with a high quality synthetic oil, at 32 to1 , you would have more build up than with the stock oil recommendation.  I think the motor would  last longer also.  I base this from racing 2 stroke motorcycles for 30 yrs.  High quality synthetic oil is superior.  Noticibly.  Especialy two-cycle oil, in high reving situations.  I think the oil is more important than the ratio(not an amsoil 100to1 fan).  A high quality synthetic oil will lubricate well at 50to1, but it will have better power and lubrication at 32to1 with no negetive effects.  All of this is just an opinion not fact.

[bwalker]

Doc, would you care to tell us the differance bewteen Stihl orange bottle oil and a oil from say 1984? Are both not API TC oils both formulated with a mixture of light petroleum base oils, a heavy petrol brite stock and additive package made with a calcium based detergent?
 Advancments have been made in lubrication, but the saw makers havent really picked up on this until the last few years. They have now began to use PIB blended oils to increase cleanliness over the old brite stock based oils.
 

If you ever have a chance to look through Stihl's engine failure diagnostic manual you will find that running a mixture too rich say 33:1 leads to excessive carbon build up and piston scoring on the exhaust port side and ring sticking as the carbon build up falls back in on the piston

Again, there is no build up with the proper oil. All of the jap motor cycle companys spec 32:1 ratios, even with dino oil.

[StihlDoc]

In the USA, the percentage of bright stock was changed and the treat rate and chemistry of the additive also changed in 1989 when the mix ratio recommendation and bottle sizes changed from a 40:1 to 50:1 mix ratio.

[bitternut]

StihlDoc I am getting confused as heck following this thread. I use Stihl oil that comes in the small bottles ( 2.6 oz I think ). I mix it to one gallon of fuel. Could you tell me if I am right in doing so. I run this mix in my Stihl 026 Pro winter and summer.

[sawguy21]

You people south of 49 need to go metric. One 100ml bottle to 5 litres of gas = 50:1. Simple The imperial system drove me nuts. I needed a wall chart with all the different mixes in the old days. 2.6 oz to the U.S. gallon sounds about right.

[beenthere]

StihlDoc I am getting confused as heck following this thread. I use Stihl oil that comes in the small bottles ( 2.6 oz I think ). I mix it to one gallon of fuel. Could you tell me if I am right in doing so. I run this mix in my Stihl 026 Pro winter and summer.

UR doing it right. Says right on the bottle that it is to be mixed with 1 US gallon of fuel (I use premium as it doesn't have ethanol in it).

[Rocky_J]

when all else fails, read the directions on the label... 

[Todd]

Its all so clear now!!???

[bwalker]

In the USA, the percentage of bright stock was changed and the treat rate and chemistry of the additive also changed in 1989 when the mix ratio recommendation and bottle

Which is a the same approach that was used in the early 80's.

[StihlDoc]

Run what your instruction manual states or whatever ratio and brand of oil you are comfortable with and have confidence in. If you elect  to use something different than a manufacturer recommends, don't complain that the product is not up to standards if you happen to experience lubricant or combustion deposit related failures in the future.

The amount of oil to gasoline in the USA to achieve a 50:1 ratio is:

1 gallon gasoline to 2.6 ounces oil
2.5 gallons gasoline to 6.4 ounces oil
5 gallons gasoline to 12.8 ounces oil

Items to note for small air cooled two-stroke engine lubrication:
a) Small changes in mix ratio won't be noticeable to you or the engine (e.g. 40:1 vs. 50:1).
b) Higher mix ratios (e.g. 50:1, 80:1, 100:1) allow the engine to produce more power as long as the oil has the necessary lubrication properties to overcome friction.
c) Don't run outboard motor oil in high performance chain saws and don't use high performance chain saw oil in outboard motors.
d) Synthetic oils are usually better performers than petroleum oils.
e) Manufacturers do extensive testing to come up with an oil formulation and mix ratio that has a reasonable price and works well in their products under most circumstances.

[bitternut]

Thanks, I will continue as I have been at 50:1 with Stihl oil.

[clyde]

stihl-doc
why do you get more power when running less oil in the mix?
I don't believe this to be true.
testing has shown us that a two-stroke motor makes more power with more oil in the mix all the way until the spark plug will foul.

[StihlDoc]

The BTU energy in gasoline creates power. Oil is not as volatile and does not produce the heat energy that gasoline does. But oil does reduce friction and helps piston rings to seal. It is possible that you could feel an increase in engine power by adding more oil if the engine cooling is not efficient, the piston/cylinder tolerance is tight, or piston rings are worn.

[bwalker]

Mac authored a SAE paper int he 70's that conlcuded that a two stroke made more power as the mix ratio was decreased up untill plug fouling became a issue.

"The BTU energy in gasoline creates power. Oil is not as volatile and does not produce the heat energy that gasoline does. "
Wouldnt oil have a higher BTU than gasoline and it sureley produces heat energy when it burns.

[clyde]

Mercury outboard motors came to the same conclusion also.
It really doesn't matter what the btu's of the oil is.  It is really not burning in the cumbustion(not much anyway).  This is why the engine runs leaner with a higher oil ratio (less gas mixed w/same amount of oxygen).  The oil volume isn't even figured in because it is not burning.  Most of the oil is burned off in the muffler.  The increased power (dyno-proven time and again) is more due to better ring sealing (higher compression) than less friction (not a bad thing).


****32-1****

[kkesler]

What would the consensus be on the appropriate mix for my Homelite C-5 with modern oils?

Here is what it says on the saw:
http://www.keslers.net/images/open/c5-mix.jpg

(16:1)