GAS: Regular? Premium? Ethanol?

[jymbee]

When I bought a new Stihl trimmer (130 FS) and chainsaw (Husky 576 XP Pro) a while ago I switched from the 87 octane gas I've always used in my older trimmers/saws to 89 octane. Since then I've talked to some folks who say to use premium gas and ideally ethanol free premium. I switched to 89 octane now.

But my older gear is at least 10 years old and still runs well today-- no issues that would seem to have anything to do with the fuel.

My question is do newer engines somehow benefit more from premium gas than older models did, or is the advice to go premium just a matter of eliminating as many potential issues as possible?

For example, if theoretically two identical chain saws ran over an extended period of time under the exactly the same conditions-- one using regular and other high test fuel, would there likely be a noticeable difference in maintenance?

 

[dusty3030]

My opinion only.

No difference in maintenance, fresh water free gas is what you want, no matter the grade.
Ethanol free is mo better no matter the grade.
89 octane is never a good buy. Either get regular 87 or get premium. Mid grade is just the two mixed.

 

[nybirdman]

I would stick with 87 octane,I am trying a product called "Startron" in my outboard motor.I just use "stabil" in my saws with no problems,and my saws sit a lot between uses.The local marina has 91 octane,ethanol free during the summer months but I will use it only in by boat.

 

[joshuabardwell]

My understanding is that higher-octane gas is only necessary for high-compression engines, such as those with a turbocharger. The higher octane resists precombustion ("knocking") at higher compression ratios. In engines running at lower compression ratios, the extra octane is totally wasted. I only put 87-octane into my yard equipment. If I ever notice it knocking, I'll reconsider ;-)

 

[RobertN]

We have a friend that is a pro arborist. Real tree doctor, not just trimmer.

His take is, these little motors are 10,000+ rpm machines; run them on good premium and a high quality mix. They are, like little race motors.

 

[imgone52]

One of our local small engine repair services says that any gas with ethanol should be treated. Either Stabil or one of the others designed for this use. The treatment helps prevent the "goo" or "gel" that plugs the carbs and fuel systems. My small mower and saw are running fine with this mix.

 

[sam5570]

i have had to replace all my fuel lines and rebuild carb on jd mower because of ethanol now thankfully we have acouple marathons station that carry a 90 octane no ethanol gas has worked great in all my small engines i even run it in my old 86 f 150 pickup with stp gas treatment

 

[PhoneFarmer]

I have been using ethanol free gas in all my lawn equipment with no problems. Sometimes my chainsaw sits for 3 or 4 months between uses and starts right up.

 

[s219]

Octane level is not so important in two strokes. But avoid ethanol if you can. If you have to use ethanol fuel, don't let it sit in the equipment for too long -- empty the tanks, and run the engines dry to get the fuel out of the carb.

I go out of my way to buy ethanol free gas for use in my chainsaws. A 5 gallon tank will go a long way with chainsaws.

 

[Bird]

I have a Mantis 2 cycle tiller and the manual says to use "89 octane". And I have a Stihl string trimmer and the manual says to use "mid-grade with a minimum of 89 octane". And I don't even know of a place in this area where I could get ethanol free gas. So I use the mid-grade gas with Stabil and with Stihl HP Ultra (synthetic) 2 cycle oil. Five years with the Mantis and 7 with the Stihl and no fuel related problem yet.

 

[MossflowerWoods]

Like Bird I cannot get ethanol free gas, (yes, the lake is too far away).

I burn premium in both my Stihl saw and trimmer, with Stihl oil. I bur regular in the mowers, blowers and generator.

I run the generator, saw, & trimmer dry before I store them (because my dealer said too do this).

Be well,
David

 

[clemsonfor]

Use premium, i know it says 89 in the manual, but the premium wont hurt it and get it ETHONOL FREE. The oil u use if you use quality stihl oil or husky will have a fuel stabalizer in it and i have not had a problem using it after 1 year. I have run premium or mid in my stihl and had it for 8 years no problem. i heat with wood and use to cut wood for family before that.

Trust me you dont want the junk that the ethonol gas forms. Its makes crystals that are hard. they almost look like seasalt or table salt or sand inside your carb float bowl and plugging your jets. Before it totally dries its a goo, that wont really suck through your jets either, kind of like a vaseline. Buy quality fuel!!!!! Best practice is to dump it after 6 months or so of sitting. I put it in my pickup (there 22 and 32yrs old) or will put it in the lawnmower and then get new fresh fuel to run in the tiny 2 strokes (my saw is $500 maybe more now a days?)

 

[huskerhayman]

My understanding is that higher-octane gas is only necessary for high-compression engines, such as those with a turbocharger. The higher octane resists precombustion ("knocking") at higher compression ratios. In engines running at lower compression ratios, the extra octane is totally wasted. I only put 87-octane into my yard equipment. If I ever notice it knocking, I'll reconsider ;-)

Turbo engines have less compression.

 

[2LaneCruzer]

I use ethanol free premium in all my stuff; they say the chain saws/trimmers, etc. run cooler with the premium gasoline.

 

[sailorman]

I have a stihl 230 chainsaw. The manual says ( yes I am guilty of reading it ) 89 octane lead free gasoline or higher . Reason stated is that lower octane may cause engine over heating . As a personal rule I only use ethanol free ' cause I can get it .

I 'll stick with the manufacturer 's recommendation .

 

[ruffdog]

I read a while ago that the fuel octane drops when you mix it with oil so that is why you start with a higher octane fuel. Another problem with ethanol is it will boil at a lower temp than non ethanol fuel.

 

[Pete Judd]

Seems like most of the loggers here run the 87 ethanol gas in their saws. I have a couple of stihl saws and trimmer, and don't have problems with it.

 

[joshuabardwell]

I read a while ago that the fuel octane drops when you mix it with oil so that is why you start with a higher octane fuel.

But isn't the flip-side of this that 2-stroke engines are designed to run in a gas-oil mixture? So the question is, what octane fuel are they designed to run off of? And I submit if they required 93-octane, or whatever, the owner's manual would say so--just like the owner's manual of my car's turbo-charged engine does. So I submit that small engines are designed for 87-octane, unless specified otherwise, and putting higher-octane fuel in has little or no advantage. Again: it's my understanding that higher-octane gas offers additional knock-resistance, but that's it. So an engine that is computer-timed can run higher compression and get more horsepower with higher octane gas. But your chainsaw isn't computer-timed. It runs the exact same timing whether you have 87 octane or 93 octane. And therefore, if you put higher-octane gas in it, it's not actually benefiting from the additional octane. Unless you're the type of person who can and will adjust the timing of your chainsaw, in which case more power to you.

BTW, some have made the case that higher-octane fuel is better because it often comes with detergents and so forth that are not in lower-octane gas. This depends entirely on where you buy your gas from, but is independent of the argument about octane itself.

 

[scrappy isb67]

Turbo engines have less compression.

the wife's car is turbocharged and running 12:1 compression. just because it is turbocharged does not mean it is lower than NA. especially in modern engines.

 

[huskerhayman]

the wife's car is turbocharged and running 12:1 compression. just because it is turbocharged does not mean it is lower than NA. especially in modern engines.

What is it? A diesel?