What's worse for my saw...

[ohsoloco]

...low octane fuel, or high octane with ethanol    There's only one station in the area that I know of that doesn't put ethanol in their gas, and a few years ago they quit carrying 93 octane in favor of diesel fuel.  The highest octane fuel they carry is 89.  I've been buying high-test from stations that use ethanol.  Is the 93 (or maybe it's 92) octane with ethanol the lesser of two evils 

[Sprucegum]

I have read in previous threads that the ethanol/alcohol destroys rubbers seals.

I would go with the low octane gas and buy an additive to boost it a bit.

[Reddog]

89 is just fine for a stock saw.

[ohsoloco]

Good to know.  I just remember that after buying my chainsaw--Jonsered 2165--that the dealer called me after getting home b/c he forgot to tell me to put high octane gas in it. 

[Holshot14]

Is this theory true for new saws as well? In reguards to the seals go bad with eth. Fuel

[Al_Smith]

 The seals are made of Buna-N which will hold up to a certain amount of ethanol .

What the stuff attacks is the carb innards .The last several carb kits  I have purchased contained certain parts which evidently have been redesigned which are more robust for use with ethanol mixed gasoline . I only assume that most modern saws use these types of gasketing in the carbs .

I run hi test but then again I have a few saws with higher compression because of being modified . Your only talking 15-20 cents more per gallon and in a saw it isn't like you are pouring in out of a 5 gallon bucket or something . Plus the fact in this area they really don't sell that high of ethanol mix in the gas .

[edwardj_]

I work at a shop that used to seel Jonny saws and now we only sell Stihl saws..   We have not had any fuel related issues from saws running fresh regular fuel.  The Stihl brand mix oil has a stabilizer in it.  I would suggest that if you use a good name brand of mix oil that the regular fuel will be fine.  I would stick to that.

[ohsoloco]

edwardj, I'm not sure what you mean by "regular" fuel.  Do you mean low(er) octane, or the "regular" stuff with ethanol in it 

[ohsoloco]

Interesting, I just checked the manual for my saw    and it says the minimum octane rating is 87.  I never bothered to look since the guy that sold it to me (who sells nothing but Jonsereds) told me to use high-test 

[Warbird]

IMO, using gas with ethanol is worse for your saw than using 87 octane.

[Jasperfield]

When you mix oil with gasoline the octane rating is reduced by a point (or 2). I use mid-grade gasoline and like the results.

[edwardj_]

By regular fuel I mean the lower octane rating.  None of the saws we sell have issues with it.  A lot of our customers used the dyed fuel we have here.  It sits in the tanks for extended periods of time and should be graded at less than 87 octane...  they still seem to run just fine.  I would stay away from the Ethanol.  Decide what fuel you want to use and mix it to the specs that you are asked to run for your machine, then adjust the carb so that it will have the proper fuel at max RPM and it will run perfect even on the lower octane.

[Al_Smith]

If you cut to the chase it probabley doesn't make that much difference what you run in a stock saw if you only have a few saws as most appear to have on this site . You are always running fresh fuel in them .

You take a guy like me with a shed full of both antiques and some modified saws you can't run them all in a timely fashion to even keep them limbered up . As such in time you become very good at rebuilding carbs .Just the way it is .--I order carb kits a dozen -20 at a time then of course when I need one I can't find it .

[ohsoloco]

Well, if Jasperfield is correct about the oil lowering the octane rating, I'll just buy the mid grade stuff from the place where they don't add ethanol.  Although I liked the idea of mixing my saw gas with fuel I already have in my 5 gal. can.  I only mix one gallon at a time...the way I saw it could last me a weekend or a couple months.

[Al_Smith]

 I think most or you are worrying for nothing .

On a stock saw use whatever you feel comfortatble with,good oil 32-40-50 to one .Whatever floats your boat .Just make sure the carb isn't set lean .

If you don't use the saw on a regular bassis run it dry before you put it on the shelf,no problems .--Much ado over nothing IMO .

Keep in mind I have 50 year old saws that run like they were brand new .Yes I've rebuilt carbs,a bunch of them but never lost a seal yet on those old duffers ,unless it was from a bad bearing . The fuel didn't eat it up for sure else they would all be leaking .