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.