View Full Version : Mixed gas.

10-26-2003, 12:54 PM
What ratio of gas to oil do you all use? It seems like more and more equipment these days are going from 32:1 to 50:1. I run 32:1 but i think its too rich for my redmax trimmer. But my homelite hand-held blower says run 32:1. Rich is better then lean, isn't it? guess i could go in between somewhere like 40:1 but i don't wanna damage anything. Thoughts? Opinions?

10-26-2003, 01:11 PM
I run 50:1 in everything even the old homelite and it seems to run fine. I use synthetics though so the oil brand and type does make a big differance. The homelite is the only thing that recamends 32:1 and if you run to rich with the oil it will clog up carbs and muflers and ports so it could mean more maintenance. I don't think 50:1 will hurt your homelite if you use the better oils.

10-26-2003, 01:15 PM
check your manuals! i surprised myself one day. i was reading through my shin. trimmer and shin. hedge clipper manuals and discovered that one uses 40:1 and the other 50:1 and they use the same engine!

10-26-2003, 01:24 PM
I run 50:1 in all the small stuff. And yes, rich is better than lean. Not enough oil in the mix and your equipment quits...plain and simple.

10-26-2003, 02:19 PM
I run 50:1 in everything, but the only thing that I have that does not call for it is my Shin EB240 and it 40:1. I have had no problems w/it. I also agree w/Rod that a little rich is better than lean.

10-26-2003, 10:58 PM
Have an old Lawnboy that requests 32:1, and an old (early 80's) Poulan Chainsaw that requests 16:1.

They've been getting 50:1 for over 10 years, and the last 4years everything has been getting AMSOIL Synthetic at 80:1.

No more muffler or plug cloggs, and power is great. No noticable wear that I'm aware of.

Rustic Goat
10-27-2003, 01:21 AM
mottster, why is it that you think you have a choice of oil/gas mix ratio to use? If you want the best performance and longest life out of 2-cycle equipment, go with what the mfg says to use.

David Haggerty
10-27-2003, 06:02 AM
I agree with TLS. It's the OIL manufacturer that sets the ratio. Not the engine Manufacturer.

I run all 85/1 Amsoil synthetic in Stihl equipment.

If you go getting generous with the synthetic oil you might as well buy the cheap stuff. Then deal with the carbon build up, fouled plugs etc.


10-27-2003, 06:26 AM
Running 100 to 1 in shiny stuff.

I use optio-max. (with fule stabilizer)

I've seen REAL OLD 2 cycle equipment opened right up thats used Optio-max for the full life and NO wear lines on pistons and Blocks.................ONLY original machining lines.

But I mix at 100 to 1..........Yes thats right 100 to 1.
Thats what the MFG of Optio-Max recomends. ALL my 2 cycle equip runs spot on and WILL continue to run that way.

YES...........Depends what sota lube you running...............They kn ow whats good for ya machine!
The MFG is ALWAYS going to recomend thier Lube at their mix though.

Use what your stuff runs well on!...................Could take a while.

Its all trial and error.

Buy in SMAll amounts and when it's time to make up a new mix (with a different MFG lube to see whats the best), make sure you run the pice of equip till empty.
Then you'll know what the go is with how your equip runs with different lubes and mixes.

10-27-2003, 07:48 AM
Same as Pinnacle but I use Amsoil synthetic. That engine does not know the difference between 100:1 synthetic or 32:1 petrol. Synthetic at 100:1 or 80:1 if you are a bit squeamish is adequate to lubricate any 2 cycle engine.
I have used it for 8 years and I have never had a 2 cycle engine failure. It is in all string trimmers, Lawn boy trim mower and the backpack blowers.
You will find less smoke, less carbon build up, more power and responsiveness. It is very simple to mix and I will never use a manufacturers petrol 2 cycle oil again. Give it a try, you will like it.

10-27-2003, 10:02 AM
I run and have always run 32:1. Yes, I have wet exhausts, but it's on 10 year old equipment that runs strong as new.

10-27-2003, 11:36 AM
I'm sold on high ration mixes using Amsoil with one exception. I will only run 50:1 in my 2 cycle Toro Proline. I have heard of too many bearing problems developing in this engine when higher ratios are used - even with Amsoil. Since I have to run 50:1 in the Toro, I run 50:1 Amsoil in everything. I realize that cheaper oil could be used at 50:1, but I believe that the Amsoil foils plugs and mufflers less and it seems to burn much cleaner.

10-27-2003, 01:37 PM
I've used opti-2 for quite a few years and no problems yet, but I always mix it a little rich.

Keep in mind though you are probably not gaining any power from the synthetic oils at 80-100:1. The oil is usually more slick but you have to remember you are running the engine richer. Most people dont have their machine adjusted (or cant) after they run the synthetic oil. Most manufacturers set the machines up for ~50:1 when you mix the gas at 100:1 your engine is running rich and 25:1 your machine is running lean. The oil takes up room in the mixture.

If you run rich you will lose some power, but in my opinion this is better for the life of the engine.

10-27-2003, 05:46 PM

You speak of "rich" and "lean" but in 2 cycles that can mean TWO totally different situations.


Rich means a gasoline rich mixture in an engine.
Lean means a high oxygen content in the mix.


In a 2 stroke.....

Rich tends to mean a HIGH oil to gas content (ie: 16:1 or 32:1) More smoke and less power.

And Lean tends to mean a LOW oil to gas content (ie: 50:1, 80:1, or 100:1) Less smoke and more power.

So, I'm a bit confused at your statements.

10-27-2003, 07:36 PM
My mix equipment is mostly stihl, and I use the stihl oil with that, at the ratio they recommend. Not even sure what it is, 50:1 maybe? I just dump a bottle in to the gallon of gas, it's all done for me, I don't have to think. Easy.

10-27-2003, 07:46 PM
I use Shindaiwa "One" oil. The mixture is 50:1. I use it in everything. I'm not going to carry 2 or 3 different 2 cycle gas cans around.

10-27-2003, 07:55 PM
Rustic and BSD you guys seem to be the only ones that run different than 50:1. I mean no disrespect but why is that. Please explain more to us as I only run 50:1 syn in all my stuff, even chain saws and the homelite gets used reguraly. The homelite I really don't worry about so it gets what it gets, but the chain saws I care for and they have been running fine for years.

10-27-2003, 10:44 PM
TLS - That is a very good point.
When I speak of rich and lean I'm talking about gas to air ratio.

On a two stroke engine the oil seperates from the gas after it reaches the carberator and goes through the jet (or needle). This means the ratio of mixed fuel to air (your high speed adjustment) is set with the oil still in the fuel. For that reason when you decrease the amount of oil mixed with the fuel you are in fact making your mixture richer because there is more pure fuel mixing with the air as it enters the cylinder.

A rich running engine has too much pure fuel vs air.
A lean running engine has too little pure fuel vs air.

The oil is always related though. If your good at math it's like solving for two variables at the same time, a change in one changes the other.

10-27-2003, 10:58 PM

I believe in your two above posts you are confusing me and you (and possibly others).

Lets just pick TWO mixes. We'll leave out the Dino vs. Synthetic lubricity variable.

One is 32:1, and the other is 100:1

The 32:1 (this is what I call 'Rich') has more oil in it, thus less possible power (less actual pure gas), and more smoke and carbon buildup.

The 100:1 (this is what I call 'lean') has LESS oil in the mix, makes MORE power (more gas in the mix), and will smoke less and eliminate carbon buildup. BUT may cause slightly more internal wear.

But the above rich and lean are terms used to describe the content of oil in the mix, NOT the actual engine A/F ratio.

Are we square on those facts?

Then you go on to say the carb seperates the oil from the gas....thats where you loose me. And you go on to say that a rich running engine will loose power, but is better for the engine.

Oil is good for bearings and rings, but NOT for sparkplugs and mufflers.

Gas is good for POWER.

10-27-2003, 11:39 PM
TLS - LOL you are making me think on this one.

Good idea with making one variable the control.

Ok, I think the best way to describe this is there is a lean and rich for both the fuel to air and fuel to oil mixture.

Lets hold another thing constant, the carb is not adjusted between the two mixtures.

This makes us not square.

When you have your RICH mixture with lots of oil you will get more smoke and buildup. However you might get a slight bit more power because the air intake remains the same and the pure gas volume is reduced. On a un adjusted carb this will run the engine slightly lean and give a little more power. Engines come from the factory a little rich (that is the extra power I'm talking about).

When you have your lean mixture with less oil your lower main bearings, upper bearing, rings, pin, and piston you will actually have more pure gas flowing into the engine. This causes more fuel to mix with the gas then the carb was set for. This rich mixture will degrade the performance slightly.

Let me go to the extreme. Your super rich mixture would be lots of oil, lets say 7:1. If you put that in your engine there will be lots of air flowing in but very little gas. This will be a very lean condition and you will burn up your engine. Your piston and rings will be fried but your bearings will be loving all the oil.

to the other extreme. Your super lean mixture lets say 250:1 would give very very little oil to lube the bearings etc but the combustion chamber would have lots of fuel and would be running rich.

Any way you put it it will not make much of a difference in our engines. I'm not trying to have a war with you TLS.

Thanks for making me think though. :)

10-27-2003, 11:56 PM
Actually the richer the oil/fuel mixture, the leaner the fuel air mixture. Why- because at any given carbureter setting it will draw in a set amount of liquid. In this case a mixture of gasoline and oil. If you are running a 50 to one (2%) oil to fuelratio as oposed to a 20 to one(5%) fuel oil ratio you can see that the gasoline to air to air mixture will be increased . (less oil in the mixture=more gas in the mixture. = richer fuel to air miture=leaner oil to fuel mixture.

10-27-2003, 11:59 PM
All I can think about right now is how bad at spelling I am and how much I want to modify my br400. I could take off the air filter. Use a grinder and open up the carb (make the air intake larger). Polish the intake going to the cylinder. Port out the cylinder. Use a thinner gasket to decrease the squish. Put a larger jet in the carb and tune it up.

Man I could have the best blower on the block, nevermind the fact that I would have to rebuild it after 5 hours or so. For that 5 hours I would be moving some leaves!!! :) :)

10-28-2003, 12:01 AM
Thats what I'm trying to say barnard.

Someone understands :D :blob3: :D

10-28-2003, 12:02 AM

10-28-2003, 12:06 AM
G-father your on the money I hadn't read you r last post when I was making my post. Nice to find someone who really understands fuel and engines

10-28-2003, 12:13 AM
so really since no power is added either way it just depends on if you want longer life, harder starts, carbon build up, smoking or shorter life, easier starts, less carbon, less smoking.

to me the leaner of the oil to fuel mixture you run the cheaper it'll be...but you'll be replacing you 2cycle equipment sooner then if you run rich mixtures. Decisions, decisions...

10-28-2003, 12:16 AM
G-Father now that we've agreed for a while. How about this . As far as changing jets in the carb- lets gat of our bikes and hold our blowers. All I've ever seen have adjustable high and low speed orfices. as opposed to fixed jets . Am I wrong?

10-28-2003, 12:19 AM
In a nutshell 50 to one with a good oil is fine in all circumstances. In an engine that has the carburetor properly adjusted.

10-28-2003, 12:21 AM
Mottster power is gained with a leaner mixture up to the point the piston will seize in the cylinder due to excessive heat /insufficient lubrication.

10-28-2003, 12:26 AM
I agree with the 50:1 for almost everything.

Your right barnard I don't think any of our blowers have jets in them, to tell you the truth I've never had mine open before. Which is very strange for me. When I was younger my old man had to hide his engines from me...I would always take them apart and sometimes (when I was really young) I could not get them back together again (or they had extra parts when I was finished). :D :D

Rustic Goat
10-28-2003, 12:29 AM
Originally posted by TRex
Rustic and BSD you guys seem to be the only ones that run different than 50:1.
:confused: TRex, not sure how you came to this conclusion, 50:1 is what is recommended for my equipment and therefore what I run.

10-28-2003, 12:31 AM
Me too. It started at a young age. I had too figure it all out because my old man was not at all mechanical.

10-28-2003, 12:34 AM
50:1 is great for most oils, 80:1 seams to be good for some of the synth. oils but I still sometimes wonder...

10-28-2003, 12:44 AM
I have never run the synthetics. Nothing against them and I don't doubt that they can run at leaner mixtures. BUT I run every two stroke engine from my blowers to trimmers to my 60 year old maytag gasoline washing machine engine at 50 to 1 with petroleum based oils - and have for years now without a failure. I will probably go to syns eventually. In the mean time no properly adjusted two-stroke need more than 50 to 1 At least in lawn equipment. Ina very high strung two stroke motorcycle engine- probably so .

10-28-2003, 08:13 AM
Sorry for making that assumption Rustic, I should have worded it differently. I guess what I meant was why do you use what the mfg. says to instead of what everyone else is doing. unless You mean the oil mfg. Sorry for making an azz out of you and me.

10-28-2003, 08:44 AM
I agree with g-father and barnard. I have been riding high performance 2-stroke dirt bikes for years. They always say not to mix the oil mixture too rich because the oil displaces the amount of fuel. It is a simple ratio of oil to fuel. The more oil the less gas getting to the engine. To little fuel leads to additional heat and if your are unlucky a seized piston. I have tried the Amsoil in both a dirt bike and a snowmobile at the 100:1 ratio and both engines siezed from lack of oil with in a short period of time. Other guys have had good luck with the Amsoil though. I run 50:1 in my trimmer and blower with real good luck. One thing for sure the oil:fuel mixture debate has been going on for years.


David Haggerty
10-28-2003, 09:43 AM
Originally posted by barnard
G-father your on the money I hadn't read your last post when I was making my post. Nice to find someone who really understands fuel and engines

I'm learning...:rolleyes: It's threads like this that makes Lawnsite worth my time. Thanks for the info.

I'd never understood why getting generous with the oil could actually lean out the air/fuel mix and actually burn up your rings.

I had an Echo trimmer that I returned to the dealer. I'd been tuning it by "ear" and it was siezed.

I griped to the dealer that I thought Echo cylinders had a lifetime warranty. He said not if you lean them out till you burn them up! And looked at me like I was stupid or somebody. The Echo distributor had just looked at it and could tell what had happened to it.

I really need to learn more about the "one lung" and 2-cycle equipment. Thanks for posting.

I can't locate my little Amsoil catalog. But don't they have a 2-cycle oil specifically for the larger engines? Is that what you were using? Just curious.


10-28-2003, 10:03 AM
Dave you need to be very careful when you tune any kind of engine.

First off make sure you have new fuel in your tank with the proper amount of oil (lets just say 50:1 to make it easy).

Start the engine up and let it warm up.

Wind it up to full power and find the high speed adjustment.

Listin to the engine (i do use not hearing protection)

Turn the adjustment more rich and hear the difference in engine noise. It should sound more rough. Then go slightly lean (in very small adjustments). You should notice a spot where the engine smooths out just a little and that is where you want to be. Dont go too far or you will lean out your engine and seize it.

*** Practice at your own risk*** on old engines that don't run very well.

David you can learn more about amsoil at http://www.amsoil.com/products.htm

10-28-2003, 11:24 AM
Originally posted by G-father

When you have your RICH mixture with lots of oil you will get more smoke and buildup. However you might get a slight bit more power because the air intake remains the same and the pure gas volume is reduced. On a un adjusted carb this will run the engine slightly lean and give a little more power. Engines come from the factory a little rich (that is the extra power I'm talking about).

When you have your lean mixture with less oil your lower main bearings, upper bearing, rings, pin, and piston you will actually have more pure gas flowing into the engine. This causes more fuel to mix with the gas then the carb was set for. This rich mixture will degrade the performance slightly.


I'm not trying to start a debate here, just voicing my opinion vs. yours.

This is the part that I don't totally agree with you on....

How can having an OIL RICH (32:1) mixture produce MORE power? If you bring in the lubricity and friction variables, then maybe it might spin better with more oil to the bearings and slipprier ring to cylinder contact. This said mixture will have LESS gas and MORE unburnable (non-combustable) OIL. It is know that a slightly rich (A/F ratio) is preferred over slightly lean. For both power and longevity.

So, without starting an arguement, how can an OIL LEAN (80:1) produce LESS power. You say more TOTAL gasoline is now in the A/F ratio. Certainly not THAT much more to cause a severe OVER RICH mixture that would lower power.

Have you tried my above situations? I have. And I experience noticable power increases in ALL my 2 strokes, from (16:1) chainsaws to (32:1) Lawnboys, to (50:1) Backpacks, and to (50:1) String trimmers. Every one picked up NOTICABLE power, Every one requires NO carbon related maintenance (Compared to Monthly plug and muffler cleanings), and so far Every one is living just fine (really, I ask them!). And over half have NON adjustable carbs. The days of adjustable carbs are OVER!

I would be more worried about the effects of clogged air filters before I'd be concerned about the oil mixture in relation to the true A/F ratio.

10-28-2003, 01:14 PM
David Haggerty,
I am pretty sure the Amsoil I was using was for bigger 2-stroke engines. I bought it from an amsoil dealer that recommended it for my application. That is a good question though. I will have to check into it further.

When an engine is jetted perfectly altering the amount of fuel can do several things.

Increasing the fuel
just slight increases will most likely just cause the engine to run slightly "blubbery" and reduce the power slightly
large increases will cause the engine to not run at all

reducing the fuel
just slight reductions will cause the engine to gain power but also the operating temp. will increase
large reductions will cause the engine to sign off early in the upper rpm's and eventually take a toll on your engine if not immedialtly.

Increasing the oil ratio (16:1) means that there are more particles of oil in the mixture which means you have replaced some fuel with oil. This causes the reduced fuel affect. When the mixture is to great it can also cause power loss due to spark plug fouling and cabon build up on the exhaust port.

Decreasing the oil ratio (100:1) means that there is less particles of oil in the mixture and fuel is replacing the oil. This will give you the increased fuel affect but will most likely run better than the (16:1) because of the reduced oil.

In the end I guess you could say that the change in oil has a larger affect on noticable power than the slight change in fuel.


10-28-2003, 01:27 PM
Originally posted by mowingmachine

When an engine is jetted perfectly altering the amount of fuel can do several things.

Todays EPA & CARB certified engines are running on the ragged edge of lean. No where's close to being jetted perfectly. By slightly adding more gas by leaning out the mixture of oil, you'll see more power, quicker starts, and less carbon buildup.

10-28-2003, 08:26 PM
This thread has been going on for ever.

First off the engines are not running on the ragged edge of lean. My guess is they set the engines run at peak power in condiitions like 25 degree weather at sea level. This way you could prob run it in 0 degree weather and not overlean your engine. However if you live down south where you use it in 70 degree weather with humid conditions your equiptment is running rich (air is less dense and filled with water particles).

4 stroke engines these days are not leaned to the max either. Look at the fuel savings when you put a efi system on the engine. This is because the factory set carb is NOT running very lean.

My conclusion - run whatever you want. Mix most oils 50:1 and the syn. at what the oil bottle says.

10-28-2003, 10:50 PM
Oil is cheep, engines aren't. I know some guys think that to much oil drains power.

But seriously, how much power do you really want, or need? Especially in a weedwacker. How often are you at full throttle? Most of the time you just need a little bit of throttle to get the job done.

I have a buddy of mine that not only runs a 40 to one mixture in everything he has. He also puts lead in the gas too. I think he may put lead in the gas, just to start an argument with everyone that he tells.

But I have Stihl stuff, and just dump the bottle of oil in the 2.5 gallons of gas. Easy Peezy.