Two Stroke Mix Ratios

[Kris Sundell]

I've been wondering what the difference is between oils that have a mix ratio of 32:1 vs oils that are 50:1 or 100:1. I see that a lot of new two stroke engines come with oil that can be mixed 50:1. I've got some Opti-2 that is a 100:1 mix and seems to work great.

My real question is the two stroke oils that come with mix ratios on the container ranging from 16:1 up to 100:1. I have a hard time believing that a "generic" oil can handle those dilution rates and still provide protection.

What makes the mix ratios so different?

 

[ammolab]

It is the engine design that sets the mix ratio. Newer engines may be made to use those scant mixes ...not sure if they need a special oil for that mix.

 

[MolaKule]

Each manufacturer's engine may have a different tune such as spark timing, air-to-mix ratio, amount of heat rejection, compression ratio, etc., so it is the manufacturer that determines the ratio of the mix.

The 2-cycle formulations contain combustion enhancers, Anti-Wear, Friction Modification, and sometime a solvent to make sure everything mixes thoroughly and burns with minimal smoke.

 

[Chris142]

I think the 50:1 mix ratios are mostly for emissions. Thats imo the limit for normal oils to still properly lubricate. I prefer 40:1 myself. No other reason than that ratio worked well for me in the past.

The 1984 atc250r I got back in 84 called for 20:1. It sure did smoke! The dealer recommended duralube @ 50:1. I had some engine seizures with that ratio so I cut it back to 40:1.

I was then sponsored by Neo oil that was supposed to be mixed @ 100:1. I could not make a lap around the track with that oil @ that ratio. Thing seized immediately.

 

[spk2000]

What about the super 2 stroke oils such as Amsoil that is rated 100:1. I have a Makita weadeater that claims in manual 50:1 using their brand oil. 25:1 using any other brand. Why? i don't know but have tried to use their oil most of the time and it is over 20 years old running strong and been heavily used in residential applications. Not commercial type use but very heavy weeds and extended run times for personal use.

 

[doitmyself]

The explanation that the different mix ratios is because of engine design does not explain how Amsoil @ 100:1 can be used in an engine recommending 50:1. Doesn't everyone think that there has also been oil formulation changes that explain the difference of 16:1 ratios in the 1970's vs. the 50:1 ratio of today? I do, and so did Barnacle Parp.

 

[Elkins45]

I follow the mixing recommendations of the engine manufacturer, not what it says on the bottle of snake oil. I have some two stroke equipment that doesn't run anymore, but none of it was due to lubrication failure.

 

[tomcat27]

we ran a Margay kart with a Yamaha 100cc engine. mix ratio is 16:1. Redline oil is mandated by our local track.

 

[Dave9]

It is mostly due to EPA emissions mandates.

They spec 50:1 knowing you will wear out your engine faster. 100:1 is just a foolish thing to do. Even if the engine is made with great materials and tolerances, you would still wear it out faster.

The only reason to run 50:1 or higher is to sacrifice engine life for burning a % less oil. This is what green headed eediots have forced upon society, that more equipment ends up in landfills and we pollute making new equipment, instead of sticking to the time tested, proven oil ratios used for decades.

If you have some Super Lube Oil that outperforms, that is not a reason to dilute it to the point where you just wasted money using it. That is a reason to not dilute it more and enjoy the benefits of it.

You might as well ignore the engine/equipment manufacturer rating for oil ratio if it was made in the last several years since the EPA started harassing manufacturers.

If you would rather save the environment and throw away your tools, with the misguided idea that a very low oil ratio accomplishes that, carry on, don't let reality interfere with that plan, but remember that the higher oil ratios are in fact (did you see that word "fact" I just wrote?) proven to increase engine life.

While you can put too much oil in and cause the engine to bog down too easily this is easily remedied by anyone who has things like a gas can and gas... very high tech things to be talking about in 2019? Not. It's not rocket surgery unless you use too lean a mix then try to blame someone else because of the EPA !@#$# basst4ards.

I like clean air as much as the next guy, but feel the mandates should be about per citizen levels not levels imposed upon everyone because of the worse actors.

 

[KneeGrinder]

Guys, I have burned more fuel in two strokes than probably all of you together, not being C**ky, I have burned 1000's of gallons. 20:1 30:1 40:1 50:1, and yes, AMSOIL at 100:1 a lot of AMSOIL at 100:1! all my friends and I ran AMSOIL at the race track and in the desert, in the high desert, 4k 5k elevation mountains, always 100;1. None of us seized! Cr250's, yz250's yz490's. AMSOIL was a different animal! We stopped using it about late 80's because we could no longer get it from our supplier. We were bummed, because my yz490 went 2/3 days without fouling a sparkplug. The 250's could usually make it 3/4 days on a plug back then. This was before watercooling and powervalves mind you. We all then switched to Golden spectrol 50:1, None of us had seize issues with that ratio and that oil either. We all had about the same plug life as for fouling goes. We ran a lot of race fuel also. If we ran 40:1 we had fouling issues! A large part of avoiding a seize condition is a proper tune, if you tune your motor for full power, full rpm, lean it out properly so it rev's up tight, but not too tight! And you ride it like mad man after it is properly warmed up, it won't seize. There is no need to run 40:1 and have excessive tail pipe smoke on a two stroke. Your plug should look like a coconut, if it smokes badly, the plug ain't gonna look like a coconut, and your motor ain't gonna make its full potential power.


My expensive Stihl chainsaws use Stihl silver bottle synthetic at 50:1, 13700k, 14000k out of cut, 10000k, 9000k in the cut, none of them have ever seized, and they have a lot of hours on them, and they are highly modified. I have a wireless tack to tune my saws, so my rpm #'s are not just pulled out of thin air.

 

[billt460]

Originally Posted by Chris142
I think the 50:1 mix ratios are mostly for emissions.

That's exactly what it is. Back in the mid 70's I had both a Homelite chain saw and weed trimmer. They were designed to run on a 16:1 ratio. Back then about the leanest 2-Stroke ratio you could find for lawn and garden equipment was 32:1. Even the oil injected 235 H.P. Johnson V-6 outboard I had back then would only run at 50:1 at idle in neutral. And run they did. I sold the weed trimmer before we moved to Arizona after 15 years of constant use. But I still have the chain saw. It is now over 40 years old, and still runs like a top.

As time marched on, oiling ratios leaned. All being driven by emissions. Most 2 Stroke engines used in lawn and garden equipment are all run at wide open throttle. (Weed trimmers, power blowers, small pumps and generators, etc.). Same with chain saws. With a 16:1 fuel / oil ratio, the engine is getting plenty of lubrication. After a tank full of fuel, oil is literally dripping out of the exhaust. And it produces enough smoke to send environmentalists screaming into cardiac arrest. But the engines will last forever.

As the EPA became more involved with small engine emissions, manufacturers leaned out the oil mixture's. Simply because it was the easiest and cheapest way for them to comply with the tougher emission standards being introduced. Most of these type of products are used seasonally, and for short periods of time by most suburban homeowners. So they still ended up getting a fair amount of service life out of the unit. At least enough to live past the warranty period, and not send customers running back to the store complaining.

Also, these things became cheaper to manufacture as they became more popular. As most manufacturing moved overseas in the 70's and 80's. About the same time the EPA started crying louder and louder about small engine emissions. Yeah, synthetic 2-Stroke oil is somewhat better today, which certainly helps. But 100:1 is really pushing it on any 2-Stroke. Especially at full throttle under a heavy load.

I wouldn't be surprised to see oiling ratios go to 150:1 or even higher, as manufacturers desperately try to hang on to 2-Stroke production as long as possible. Before they are outright banned in favor of 4-Stroke only equipment. Many municipalities have already done so. Even some lakes and waterways today have banned 2-Stroke outboards and PWC's because of emissions. 2-Stroke technology and production is on borrowed time. Regardless of how lean they try to run them.

 

[Lapham3]

FWIW-I've run the same 2 Jonsered saws for over 40 years and 3 Echo backpack blowers from the early 1980's. I used Optimol and later also Amsoil 100:1 synthetics at 75:1 ratio. I've had zero engine problems with any.

 

[BigShug681]

I've been running Amsoil's Saber oil at 100:1 with zero issues, in fact all my stihl equipment seems to be more responsive at this ratio and are extremely easy to start compared to when they ran on the stihl premix at 50:1

 

[MolaKule]

Originally Posted by doitmyself
The explanation that the different mix ratios is because of engine design does not explain how Amsoil @ 100:1 can be used in an engine recommending 50:1....


I don't think a 100:1 ratio CAN be used in ALL engines. The 100:1 is a "suggested" ratio.

I think you have to experiment to find which ratio is appropriate for your engine.

Here is the exact wording from Amsoil:

Quote
...Use in all two-stroke handheld equipment where JASO FD,, ISO-L-EGD or API-TC oils are specified, including STIHL*, ECHO*, Toro*, Shindaiwa*, Craftsman*, 4-mix STIHL and Hybrid 4 Shindaiwa engines.

Use at conventional mix ratios, or the SABER® Ratio™ regardless of the mix ratio specified for the equipment. For maximum benefit, use the SABER Ratio.

MIX RATIO OIL FUEL
Conventional 32:1 4.0 oz. 1 U.S. GAL
Conventional 40:1 3.2 oz. 1 U.S. GAL
Conventional 50:1 2.6 oz. 1 U.S. GAL
SABER® Ratio™ 80:1 1.6 oz. 1 U.S. GAL
SABER® Ratio™ 100:1 1.3 oz. 1 U.S. GAL



I have posted this before but this is how I determine the proper ratio:

Originally Posted by MolaKule
I would use a full synthetic 2-cycle oil such as Amsoil's Saber or Craftsman 2-cycle Oil (made by Warren distribution) with at least a JASO SB or SD rating. These oils have low deposit and low smoke formulations.

I recently acquired a Remington 25cc engine head (MTD) for Multi-Attachment use with an Edger attachment and it specifies a 40:1 mix and it works best at that ratio with a synthetic formulation.

I also have a garden tiller with a 43cc engine that specifies a 50:1 ratio and it too prefers a 40:1 ratio with a synthetic oil.

I determine the preferred ratio by listening to the engine and watching its exhaust.

If I hear the engine making a high-pitched popping noise (short explosive sounds), the mix has too much fuel. If after the engine is hot and it still smokes, the mix has too much oil.

 

[beanoil]

Originally Posted by Kris Sundell
I've been wondering what the difference is between oils that have a mix ratio of 32:1 vs oils that are 50:1 or 100:1. I see that a lot of new two stroke engines come with oil that can be mixed 50:1. I've got some Opti-2 that is a 100:1 mix and seems to work great.



First, always mix at the engine manufacturer rate, not the oil label.
Second, going that lean on oil, say 100:1 is not doing your engine any good. At idle, OK, but as RPM's and heat increase, you need more oil, plain and simple. I've run 2 strokes for 50 years now. A teardown after running 100:1 ALWAYS shows more wear than one bathed in 40:1 for the same interval. Back in the day, 2 stroke motocross bikes needed 32:1, or more, 20 or 16:1 .
Look at the many threads here about AMSOIL and their 100:1 offering. read those threads and see how many are mixing it at 50:1. They don't believe the lean ratio hype either.
Might want to look this over: 2T oil info
And now the ugly... Opti-2 is probably the worst thing you can use.

 

[BigShug681]

Originally Posted by beanoil
Originally Posted by Kris Sundell
I've been wondering what the difference is between oils that have a mix ratio of 32:1 vs oils that are 50:1 or 100:1. I see that a lot of new two stroke engines come with oil that can be mixed 50:1. I've got some Opti-2 that is a 100:1 mix and seems to work great.



First, always mix at the engine manufacturer rate, not the oil label.
Second, going that lean on oil, say 100:1 is not doing your engine any good. At idle, OK, but as RPM's and heat increase, you need more oil, plain and simple. I've run 2 strokes for 50 years now. A teardown after running 100:1 ALWAYS shows more wear than one bathed in 40:1 for the same interval. Back in the day, 2 stroke motocross bikes needed 32:1, or more, 20 or 16:1 .
Look at the many threads here about AMSOIL and their 100:1 offering. read those threads and see how many are mixing it at 50:1. They don't believe the lean ratio hype either.
Might want to look this over: 2T oil info
And now the ugly... Opti-2 is probably the worst thing you can use.

So the people running it for years at 100:1 with zero issues must be a fluke?

 

[meadows]

What is wrong with Opti-2?

 

[MolaKule]

Originally Posted by BigShug681

So the people running it for years at 100:1 with zero issues must be a fluke?


I would say they have been extremely lucky.

I have three 2-cycle machines here that have to run between 40:1 and 50:1. They overheat and seize with anything less.

Forget about castor oils. The better oils, such as Amsoil and others, have synthetic esters and other synthetic oils that are superior to castor oils and cleaner burning as well.

I posted this elsewhere:

Quote
In TC oils, the majority of components are Multi-Functional Friction Modifiers/AW's where most of the friction modifier/AW's are one or more polyisobutylenes of various molecular weights. Older formulas used brightstock but brightstock leaves a host of deposits and residues.

In synthetic TC-W3 oils, the Multi-Functional Friction Modifiers/AW's are a combination of polyisobutylenes of various molecular weights and POE's of Trimethylol Propane (TMP) esters. The TMP esters may also do some cleaning of the combustion system while in aerosol form.

In ancient TC formulas, a Stoddard solvent had to be added in order to get the brightstock and other heavy oils (Group I and II 30 grade oils) to go into solution, but TMP esters now take care of solubility issues.

Base oils may be Group III oils, and or some PAO's, but are minority components.

The additives are: a polyisobutenyl (ashless) succinimide dispersant, a phosphorylated Borate (another AW/Anti-scuff agent), and a combustion enhancer of either a sulphurized oxymolybdenum dialkyl-dithiophosphate or a Titanium-compound.

 

[jakewells]

I use 32:1 in new and old equipment no exceptions.

 

[KneeGrinder]

Originally Posted by BigShug681

So the people running it for years at 100:1 with zero issues must be a fluke?



Evidently so, I surely would not be foolish enough to argue with Mola, but as you yourself have experienced AMSOIL is different, some seem not to accept that. Kind of like the thick vs thin...lol, different synthetics vs conventional or conventional blends. I have never used any other AMSOIL products! Just 2 stroke oil.

I'm on the record, I've run atleast 1000 gallons of premix of AMSOIL at 100:1 in a yz490, and a watercooled, powervalve, cr250 that I raced on closed coarse tracks, never seized, and never any signs of abnormal wear that some are stating.

More than another 1000 gallons, closer to 2000 gallons of Golden Spectro at 50:1 in another cr250 race bike, no seize either, no signs of any abnormal wear. Golden Spectro is a blend meant for 50:1 and does not have any other solvents added like other 2 stroke oils do. There is a difference in 2 stroke oils!