Stihl recommends 89 octane

[livemusic]

I was reading a Stihl manual and it called for ethanol not more than 10%, and 89 octane. First, I am surprised they don't recommend ethanol free. Second, we can't get anything but 87 octane ethanol-free gasoline around here. You think that is okay? This premix in a can is expensive! I don't know what it is a gallon, but it's a lot.

Lastly, I bought a used ms362 Stihl that has always had 89 octane ethanol-free run it, along with Stihl silver bottle synthetic oil. If I had my druthers, I guess I would keep running the very same thing. I wonder if it matters, lol.

 

[Whitty21]

I always do my best to run 91 octane through mine, which in canada at most stations is ethanol free. But sometimes some 87 slips in there. Ethanol only really does anything bad if it sits for a while and gets gummy

 

[A10egress]

ethanol free 87 i would think is fine but Stihl made this recommendation for a reason!

 

[Shagbark]

I use 90 octane ethanol free in all my saws. No issues.

 

[1Alpha1]

What the Hell does Stihl know?

Since the introduction of flippy caps, I've lost all respect.

 

[danimal]

Aint that a flippin fact.
I run 100 LL and usually klotts super
In my 390 xp and my ms390 .
Gotts me sum circlips n waitn on me cabers to put my hogged out ported ms360 pro back together. Compression must be to low and thats why that saw gets 93 methal/ethel. See if it handles real gojuice when its ddun.
32/1 all my saws, rather scrape crud off piston n port that melted aluminum and bearings anyday.

Low octane causes pre det.
Got my xp used = abused ,cause of a logger pinching pennies who had that happen.

 

[Ironworker]

Two strokes are not as sensitive to gas as most would have you believe.

 

[Chainsaw Jim]

Low octane is what makes the top edge of your piston look like the backside of the moon.

 

[Dave27483]

In Australia we can not purchase 89octane.
It comes in 91, 95, or 98 octane.

 

[x308]

Dave, the Americans measure their octane differently to the rest of the world. (surprise)
We use RON, they use MON, which is 4-6 octane numbers lower than ours. So their 89 would be our 95.

 

[Dave27483]

Dave, the Americans measure their octane differently to the rest of the world. (surprise)
We use RON, they use MON, which is 4-6 octane numbers lower than ours. So their 89 would be our 95.

Ok thanks for that info,

 

[longbowch]

My opinion is you can use gas with ethanol if you keep it fresh. If it's more than a month old, dump it out.

 

[wcorey]

87 is fine in the vast majority of saws, even fairly high comp modded ones.
I think that's due to the small displacement and resulting relatively narrow squish band (IMO).
Detonation issues in saws usually has more to do with bad/old/contaminated gas.

@Whitty21 Ethanol does all kinds of undesirable things long before "it sits for a while and gets gummy"...

@x308 We run RON + MON / 2 over here, not MON...

 

[livemusic]

A pilot friend told me last night of a source for avgas aviation fuel. He said it's 100 octane. I don't know if they sell more than one octane rating, or more.

Is this good to use with recent vintage chainsaws? What about older saws, such as a Stihl 026?

Thanks.

 

[Mad Professor]

A pilot friend told me last night of a source for avgas aviation fuel. He said it's 100 octane. I don't know if they sell more than one octane rating, or more.

Is this good to use with recent vintage chainsaws? What about older saws, such as a Stihl 026?

Thanks.

The 100LL is color coded blue and I've ran it for years since MBTE and then ethanol were added to pump gas.

There is also a low octane red AV gas that is only fit for low compression antique airplanes. There is also green (115 octane) and purple (130) octane, they are hard to find and the purple was made for high performance military applications.

 

[livemusic]

Is there any 'need' to use 100 octane? Stihl recommends 89 octane minimum. What about mixing 100 octane avgas with 87 octane ethanol-free gas to create a blend somewhat in the middle? Is there an 'ideal' octane rating? I don't know what the avgas will cost me but ethanol-free 87 octane at the gas station costs me $2.99!

 

[Marshy]

Dave, the Americans measure their octane differently to the rest of the world. (surprise)
We use RON, they use MON, which is 4-6 octane numbers lower than ours. So their 89 would be our 95.

We use the averave of RON and MON.

 

[user 122190]

If the saw is running good, then the gas is fine. If not then get some octane booster additive.

 

[Mad Professor]

Is there any 'need' to use 100 octane? Stihl recommends 89 octane minimum. What about mixing 100 octane avgas with 87 octane ethanol-free gas to create a blend somewhat in the middle? Is there an 'ideal' octane rating? I don't know what the avgas will cost me but ethanol-free 87 octane at the gas station costs me $2.99!

No need for 100 octane but it was the only fuel available without ethanol. Recently stores started selling the quarts of ethanol free mix but $5 a quart is a bit too much $$$$

 

[Oleo-Mac 999]

Here in Portugal, we use 95 or 98 octane gasoline
Careful with gasoline with more than 100 octane!