Two Cycle Fuel Mixing ratios.

   / Two Cycle Fuel Mixing ratios. #1  

Gale Hawkins

Super Star Member
Sep 20, 2009
Murray, KY
1948 Allis Chambers Model B 1976 265 MF / 1983 JD 310B Backhoe / 1966 Ford 3000 Diesel / 1980 3600 Diesel

This hour long video is very detail and if you own a Stihl it is even more detailed.

Having seven functioning two cycle engines (saws, line trimmers, blower and generator) with different mixing ratios I have for the most part ran a 40:1 ratio to keep from going too lean on anything. To be on the safe side I do buy the synthetic Stihl two cycle mix.

The Stihl 021 I bought new about 20 years ago but it was after we quit heating with wood so it more or less new like in appearance. Back in the spring I bought a use Stihl 361 after struggling where to go with a Farm Boss or a used 361. Watching a lot of owner reviews on YouTube it seemed to be the apex of the Stihl saw lineup by many so I wound up buying a used but not highly abused 361 from an 85 year old guy who was wanting to come up with the money to trade up to the new easy pull smaller Stihl now on the market.

The chain, bar and sprocket were about 80% used up so I went new with those and a new plug then dropped some money on the Stihl head, face and ear protection and their chaps. The saw is a dream to use but it is break time after burning a tank of fuel before setting it down. :)

Recently from my sister I got back dad's old Stihl 011 AVT that I really have no idea how old it is but he did pass nearly 20 years ago. My BIL did use it but he passed about four years ago when he rolled the 601 Ford and was pinned under it. Yesterday I dumped the blue looking fuel mix and it started up fine.

Before I finished the first tank in dad's 011 AVT it started loading up and would not idle. The same thing happened with the 361 after I burned about three tanks though it in the spring. My 021 still ran OK but all it has ever ran was Stihl mixed at 40:1 instead at 50:1 per the manual.

Currently when it comes to pure gas 87 octane is the only thing I can get locally (Stilh calls for 89 octane min) so I went with the 87 octane pure gas and mixed 50:1. After I dumped the 40:1 gas with 10% ethanol and refilled with the fresh 87 at 50:1 ratio both the 011 and 361 started running correctly as soon as the gas in the carbs burned out.

The change was dramatic and instant. Learned my lesson on not following the Stihl book. Based on these three old saws I think Stihl saws are great.

I have read most engines calling for 40:1 ratio are OK with a 50:1 ratio mix if the oil is rated as a 50:1 ratio TC oil. Does anyone have any experience on this subject?

   / Two Cycle Fuel Mixing ratios. #2  
i run any 2 cycle oil i get cheep in mine i have put gas in the tank then put in the oil . dont like doing it but never hurt it yet .. and for bar oil i use old motor oil in cars works in saws .. there just a saw not a hart monitor .the only thing they do need is the right plug other then that they need nothing ..cut over 100 full cord of wood in my life so far and on two saws .and the only reason for the other saw my brother sold it to me .or it would have been one saw .
   / Two Cycle Fuel Mixing ratios. #3  
It is the concentration of the oil that determines mix ratio, not the piece of equipment. I use 50:1 synthetic oil mixed at 45:1 in all my 2 cycle engines including my father's 1975 vintage chain saw which I break out once a year for nostagia and because it is good to run it. Not an issue in over 20+ years of doing this.
   / Two Cycle Fuel Mixing ratios. #4  
I use the same mix I put in the boat motors in all my 2 cylces. One of those is a old Poulan I bought new in 1980 and runs like a champ, never had the carb apart but did have to put new fuel lines in it about 4 years ago. 50:1 89 octane using Quick Sliver premium oil. I just syphon out of he boat tank when I need some around the house.
   / Two Cycle Fuel Mixing ratios. #5  
In the last 18 months I bought a small Stihl chainsaw and a Stihl string trimmer. They doubled the warranty period with the saw if you bought a six pack of oil with it. Can't remember the ratio, but it's a bottle of oil to 1 gallon of gas.
Rather than mess with different oils and multiple fuel containers, the Stihl mix gets used in the trimmer, Stihl saw, a Poulan saw and a Shindaiwa sweeper. The fuel is always treated with K100 whenever the gas can is filled. So far, no problems with any of it other than replacing a fuel pickup in the Poulan. But that saw was purchased in 1998.
   / Two Cycle Fuel Mixing ratios.
  • Thread Starter

This morning it was doing some more reading and Google found this thread that has a lot of good info on my question. A few of you who have moved to the Stihl Ultra 50:1 for all your older two stroke seem to be pleased. I was surprised it worked fine in the posted cases even in engines calling for 16:1 ratio.

It is our HF generator, line trimmer and leaf blowers that call of the 40:1 ratio but they are only $100 or less each to replace if the Stihl Ultra 50:1 lets them burn up. :) I think I will be fine with the Stihl Ultra at 50:1 in all my two stroke stuff.

I know it was nice yesterday when dumping the Stihl Ultra 40:1 mix and going with it at 50:1 made both the 011 and 361 Stihl saws idle well and turn at the proper RPM at WOT.

When I was a kid dad used 30 wt non detergent in both the gas tank and the chain oil tank.
   / Two Cycle Fuel Mixing ratios. #7  
I use the Stihl Ultra 50:1, 89 octane gas (with ethanol), and the old red Stabil in both my 7.5 year old Stihl string trimmer and in my 5 year old Mantis tiller (bought reconditioned).
   / Two Cycle Fuel Mixing ratios. #8  
I've used Polaris synthetic snowmobile oil(till I finished the gallon jug I had), now using Echo synthetic 2stroke in all my 2strokes, Stihl string trimmer, Echo brush blade trimmer, Echo trimming saw(14" chain saw)and two old Craftsman chain saws calling for a 16:1 mix. All run fine, start easily and produce little smoke;was kinda worried about the 16:1 saws, but figured they are both over 30 years old so not much to lose there. Can't kill them, they run better at 50:1 than they ever did at 16:1
   / Two Cycle Fuel Mixing ratios.
  • Thread Starter
Was talking with a guy this morning that got tired of different ratio mixes and just when quality 50:1 several years ago and all is still well even with the one labelled 16:1. Clearly the TC oils marketed for 50:1 are better than the old 30 wt non detergent oils of yesteryear. :D

I had planned to have burned a lot of our mix by the end of the day but yesterday morning I decided to fine out why bad stuff was not running down hill and learned we had roots growing in all of the wrong places. Wife and teenage daughter's have expectations and when they are unmet it makes for noisy days. :)
   / Two Cycle Fuel Mixing ratios. #10  
my mantis tiller doesnt like to run on anything thicker than 50:1. (like wont run on it) I run all my old stihls (0xx 010av and 039) on 40:1 and they are quite happy with that.

Ive heard from friends that if you use 50:1 synthetic in everything these days, but i prefer my old school non-synth 40:1 mix myself.