Octane and 2 cycle oil

jeep461(5)July 11, 2010

Ok, most 2 cycle chain saws and trimmers are sawing it is ok to use their premium oil at 50:1 and use premium gasoline in 2 cycle engines even though they originally stated a mixture of 32:1.

What do you think? Keep the ones that originally stated 32:1 at that ratio and the newer ones at 50:1 ? Any insights would be appreciated as I now have a mixture of machines.


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I would use at least 89 octane. I myself use 91. I have no experience with older equipments that originally called for 32:1. I did read this question many times before and from responses of many people 50:1 with good quality modern oil is plenty good.

That said, as for me......just me now!! If I use normal good oil like Echo Power Blend type, I would mix at 40:1 but no more. There are test that any more oil without adjusting the carb will cause temperature to rise. At 32:1, temp rise is about 10 to 15 degrees C. That is not good. To avoid this, I am using Amsoil that is design for 100:1 and I use at about 55:1 to 60:1 to give some margin but still keep the ratio close to 50:1.

Now that's just me, I am not advicing anyone on this. Just remember do not go more than 40:1.

    Bookmark   July 12, 2010 at 1:01AM
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Jim , I would agree that with newer Oil Technology 40-1 is more than sufficient for your needs. Stil Oil is one of the leading Saw Brands on the Market. I have used Amsoil in my older saws at 70-1 with no Problems of course both have Chrome Bores and Ball or Torrington Class Bearings . The Older Saws did run 32 and even 16-1 Ratios back in the Day and required regular decarbonizing of Rings and Heads after Hourly Levels. Normally I never recommend less than a 50-1 Ratio for any 2-Stroke Application , but as said 40-1 in your Texas Heat would be a sound precaution . Lets us know how the Echo and Stihl Units serve you after your 1st season !

    Bookmark   July 12, 2010 at 5:46AM
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I just challenged myself to go to 50:1 on all my equipment. BUT! My old equipment has been too good to blow them now. IÂm on my 2nd Poulan S25 chainsaw since 1978 cutting at least 4 cords of oak per year. The 1st saw lasted over 10 years before the wrist pen ruined the cylinder. The 2nd saw lasted about 15 years before it locked-up in this TX heat. I replaced the piston and the rings and itÂs running strong today. I respect the saws and try not to use them long when the temp is above 80.

I have 2 saws 16:1, 2 blowers 16:1, 1 trimmer25:1 and 1 trimmer 50:1, IÂll live with this unless I go 32:1 with the 25:1 25 + year old Green Machine Trimmer. Regular is the only grade of fuel I have ever used in all the equipment and boat vs truck.

Speaking of saws do any of you have experience with hydraulic log splitters and find them to be too loud to use w/o ear protection?


    Bookmark   July 12, 2010 at 6:48PM
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I am out of warranty on all saws. So my only insurance is quality,fuel,oil and care. I will run it all on 40:1 Stihl or Amsoil oil. I figure with 4 saws I will switch after a tank or two. Craftsman still runs good but only for a tank a day. I just found a Western Auto that is a Stihl Elite Dealer a mile away from work. So I will pick up some oil.

Thanks again,


    Bookmark   July 13, 2010 at 12:27AM
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If you get Stihl, get the Ultra, that is the best.

40:1 with Amsoil is a little excess. I removed mufflers to check and at about 55:1 or 60:1, I can see a coat of oil film on the piston and the inside of the muffler has a film of oil also. This is true for my trimmer and bp blower. You might want to take the muffler off and make sure oil is not ozzing out if you use 40:1 with Amsoil!!!

This is a balance between enough lubrication and too much deposit which can cause stuck rings and carbon buildup. Either one will need work to fix, so you might want to keep it at a happy medium. My wild guess is 50:1 with Amsoil, you be having double the oil recommendation already.

    Bookmark   July 13, 2010 at 3:35AM
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I went by the Stihl store, they did not have any Amsoil so I bought The Stihl oil. I thought it strange to off 3 grades of 2 cycle oil. So I bought the most expensive the ultra pack. I will still look for Amsoil 100:1 and buy a quart.

Do you think Amsoil or Stihl oil would work to rebrake in a 2 cycle outboard ? I have one than has sat for 7 years and is free turning. 1st half hour is critical. I want to put my 75 Stinger on my air boat.


    Bookmark   July 13, 2010 at 11:07PM
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canguy(British Columbia)

I run Echo oil at 50:1 with 87 octane in everything including my old saws. Going heavier actually causes the to run leaner, not as much fuel is available, and lowers the octane.The carbon deposits can break loose and quickly destroy a piston and cylinder plus the increased compression raises operating temperature.
Our octane ratings are different than in other parts of the world, different rating systems. 87 would be considered high in other countries hence the recommendation for premium.

    Bookmark   July 14, 2010 at 12:19AM
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According to a very highly respected person Lakeside in Chainsaw forum where he is Stihl certified tech, unofficially, Stihl claimed you can use Ultra oil at 80:1 ratio. I think you will be very safe to use Ultra at 50:1. It is full synthetic oil supposed to be ester base.

    Bookmark   July 14, 2010 at 3:37AM
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Jeep: As for your marine aaplication , I have used premium Oil in 100-1 ratio for yrs within my Yamaha outboard as specified in the owners manual . Also used Amsoil in my Evinrude 90 HP V-4 @ 70-1 ratio. Your Stinger is 1970 or early 80's I believe so 50-1 or 70-1 should be fine also .
Run it and do a quick plug check .

    Bookmark   July 14, 2010 at 5:39AM
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Loger: Do youself and your Old Equipment a favour and run 50-1 accross the board . The new oils and fuel treatments today require much less oil to achive optimium lubricity . You are wasting money and will over time do more damage with carbon deposits and potential Demon Heat Issues within your air-cooled units . The heavist I would ever mix would be perhaps 40-1 . I can just imagine the clouds of smoke your creating lol .

    Bookmark   July 14, 2010 at 10:00PM
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Thanks for all the info. I work my equipment hard and then it sits until needed again.

Hate to get rid of my Stinger, my mechanic wants me to get a Yamaha 70. It ran superb before it was stored 7 years. So I will try to break it in again. I believe I will run chain saw oil for the 1st hour or so. From all I have read a heard it is superior to marine grade 2 cycle.


    Bookmark   July 15, 2010 at 12:04AM
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Jim: Iam an Old OMC. Fan have always swore by Envinrude . Raced Dirt Bikes and Snowmobiles for Yrs. I have found that Religious use of Premium Oils and Plug Checks to ensure proper lubrication will ensure long efficient Engine Life. I always do Plug Checks to determine engine performance . My Old V-4 90 would troll all day and cruise at 35 MPH all day . Never bought into the OMC vs Yamaha Manf. Oil issues , just made sure the oil was TC-W3 Rated. Eventually with the Amsoil Product I introduced it into my Snowmobile , Chainsaw then Outboards @ 70-1 . As for the Yamaha 70 , great outboard . I assume you are talking mid 80's vintage since early 90's they went to Oil Injection. I would buy it in a Heartbeat , can't kill the bottom end of any OMC (Stinger) but the Power and fuel conservation of the Yamaha would be like night and day lol . All the Best with your Trial , keep a eye on your Spark Plug Colouration , they don't lie !

    Bookmark   July 15, 2010 at 5:35AM
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