Stihl Fuel Recommendation?

[Geo019t]

Opening the instruction book which came with my Stihl saw, I note that REGULAR grade fuel is recommended, with a WARNING against using Premium fuel. I have been of the belief and practice (for the past 49 years ) that the higher the octane, the better: High octane enables the saw to run cooler, as well as minimizing problems associated with lo-octane fuel.
To suggest I'm confused might be an understatement!
Any comments or suggestions?
geo

 

[huskydave]

You don't need premium unless you bump up the compression, that said premium has less ethanol in it generally and has more additives in it that are supposed to help. If your not running the saw often then running it dry at low rpm and pouring out the bar oil is a good idea. You can buy engineered fuel that is mixed 50:1 from a small engine dealer but it is pricey and one can only fills the saw up a couple times. That fuel is very good though and has a long shelf life. I use good oil and premium fuel on every small engine I own.

 

[Chevboy0167]

https://www.2strokeheads.com/index....-octane-fuel-and-the-definition-of-detonation

https://www.eia.gov/energyexplained/gasoline/octane-in-depth.php

 

[Geo019t]

You don't need premium unless you bump up the compression, that said premium has less ethanol in it generally and has more additives in it that are supposed to help. If your not running the saw often then running it dry at low rpm and pouring out the bar oil is a good idea. You can buy engineered fuel that is mixed 50:1 from a small engine dealer but it is pricey and one can only fills the saw up a couple times. That fuel is very good though and has a long shelf life.

OK, thanks -- but here is the challenge: The ONLY Ethanol-free choices I have are (too far and too costly) fuel at nearby airport; OR, Premium Ethanol-free at local EXXON-Mobil station. In addition to, "which is worse -- the high-octane or the ethanol?", does the premium in fact have additives which harm my saw?
One thought I had is Stihl serves the entire world! My only gasoline source comes from New York State, USA stations. E.g., is the fuel I pump of the SAME formula as in any/all of the other countries -- where perhaps "Benzol" is added?

 

[huskydave]

The premium won't hurt anything but it isn't needed until you have a higher compression engine or something that is boosted, like a car with a turbo charger. Those engine will ping if run on regular and be more prone to detonation. I run premium for years and years without trouble in saws but a lot of people just run regular and it works fine. When I get fuel I put some in the truck first before filling my can because the lines will have whatever was last pumped in it, usually regular fuel. I don't keep fuel around for more than 1 month personally. You want to go to a place that sells a lot of fuel to get the fresh stuff.

 

[cookies]

get the premium non ethanol at the gas station, adjust the carb for it and move on. do not use fuel below 89 octane in a saw, it lowers the octane rating adding oil.

 

[PJwoodcutter]

The fuel rating in the manual that came with the 500i saw I bought is minimum 89 octane with no more than 10% ethanol.

 

[Sidecarflip]

Pretty much anything over 10% corn alcohol is detrimental to any small engine, 2 stroke or 4 stroke. Why I run canned fuel, that and I don't run my saws a lot.

 

[ballisticdoughnut]

I’ve run 87 to 100+ octane fuel in near every kind of small engine two and four stroke equipment. They all ran fine and still run to this day. Run whatever grade of pump fuel you want it’ll be fine. Preferably non ethanol of course.

 

[user 196652]

I have two choices here so I run the 98.

Premium 98 octane
Benzene 71-43-2 0.1 to 1.0 %
Gasoline, natural 8006-61-9 90 to 100 %
Plus:
Friction Reducer
Cleaning Agent
Rust Inhibitor

91 octane
Gasoline, natural 8006-61-9 80 to 100 %
Toluene 108-88-3 0 to 20 %
Cumene 98-82-8 0 to 20 %
Benzene 71-43-2 <1 %

 

[muddy42]

Reducing ethanol content should be your priority. Plus use fresh fuel, a month or two old maximum. Ideally keep fuel and machines dry indoors. Engineered fuels work well, yes they are expensive, but you only need to avoid one lean engine failure to recover the cost. I use engineered fuel in infrequently used machines and pump petrol in the frequently used ones.

 

[ChuckMI]

I once worked in a plant of one of the big three automakers. They had a mysterious warranty issue of spark plug fouling. They eventually found out that the fuel supplier had run out of regular and substituted premium without telling the auto company since everybody knew that premium was better. The premium gasoline caused the fouling. I use 89 octane in my chainsaw and trimmers, presumably with ethanol, and never have a problem. BUT, I plan my work to run the tank dry within a few days of filling it and do enough work that the purchased fuel in the containers is always used within a month. When the equipment is stored for the season, it is dry.

 

[Sidecarflip]

What I do with my seasonal power equipment like zero turn mowers, tillers and other seasonal stuff that sits all winter unused is, I drain out the pump gas, run them dry and add a pint or 2 of canned gas and run that through the carbs or EFI and then let them sit in the barn all winter (I remove the starting batteries as well), That way I know they will start right up in the spring and no worries about phase separation and clogged up fuel systems. I've cleaned my share of gunked up carbs and replaced deteriorated fuel lines in the past. The diesel tractors get their fuel tanks topped off and I add Powerservice Bio-Kleen as well. I've dealt with algae in diesel fuel before and it's always expensive to recify.

 

[SCMtnHaul]

Ethanol is one of the worse things to happen to gasoline. My local small engine repair shop once told me around 25% of their repairs are due to regular pump gas sitting for too long in the carburetor. For occasional use just pay more for the ethanol free and save money and headache on a repair, or at least run a little ethanol free through the carb before running it dry for storage. A former Honda employee who lives nearby, he worked in their carburetor division, swears by the ethanol free fuel for guaranteed starts.

 

[huskydave]

85 percent of the engines I fix are fuel related.

 

[Sidecarflip]

Corn alcohol in gasoline is and has always been a total looser. Reminds me of the new (no spill) gas cans that spill fuel everywhere.

If it wasn't for Gummit subsidizing the distillers, none would be in business.

 

[Doorfx]

My ms170 calls for premium

 

[Doorfx]

Ms241 C-M calls for mid grade.

 

[Doorfx]

STIHL 034 super calls for mid grade.

 

[huskihl]

Fresh and no ethanol. Higher octane fuel stays fresh longer and doesn’t boil as early in a running saw