fuel for 2 cycles: the higher the octane the better? (1 Viewer)

[e9999]

seen in a couple of my saw manuals (Echo and Stihl) now that they recommend 89 octane (US) for the mix. Another (Stihl) one said 87. Did see a comment about how lower octane can make the saw run hotter someplace, though. Does that mean that 91 octane is even better than 89? I'll splurge and use 91 for the chainsaws and wackers if it's good for them. Yea or nay?

 

[WarDamnEagle]

I just bought a Stihl combi with the trimmer and edger attachments as well as their largest handheld blower. The dealer told me to use higher octane with the mix but he didn't specify. I understood him to mean anything higher than 87. He said that they were having problems which they were attributing to the 10% ethanol mixes and that running higher octane helped. I don't recall exactly what the problem was, maybe carbon build up?

 

[fj40charles]

89 Octane is all you need. Anything higher, you're wasting money. I believe Stihl specs their chainsaws at 89 octane.

Here is a tip I got from Chainsaw King D'Animal... Don't think you're going to get a gallon of 89 octane at the gas station when you fill your 1 gallon gas can. You need to run the gas for a while to flush out what was in the hoses/pipes before you get 1 gallon of the specified octane. The only way to avoid this is if you find a gas pump with 3 separate gas nozzles.

I fill up the car with a couple of gallons before I fill the 1 gallon gas can.

 

[fj40charles]

One more thing. Don't be a cheap bastard and buy the cheapest 2 cycle oil. Buy Stihl Ultra synthetic if you want your quality/expensive equipment to last.

 

[e9999]

89 Octane is all you need. Anything higher, you're wasting money. I believe Stihl specs their chainsaws at 89 octane.

Here is a tip I got from Chainsaw King D'Animal... Don't think you're going to get a gallon of 89 octane at the gas station when you fill your 1 gallon gas can. You need to run the gas for a while to flush out what was in the hoses/pipes before you get 1 gallon of the specified octane. The only way to avoid this is if you find a gas pump with 3 separate gas nozzles.

I fill up the car with a couple of gallons before I fill the 1 gallon gas can.

very good tip indeed!

 

[naturalite]

One more thing. Don't be a cheap bastard and buy the cheapest 2 cycle oil. Buy Stihl Ultra synthetic if you want your quality/expensive equipment to last.

I have always liked buying synthetic oils for my two stroke, but if you go to their website this is what it says about their ultra synthetic, it bio degrates by 80 % in 21 days. I bought it once and that was it. Read the last line.
STIHL HP Ultra 2-Cycle Engine Oil
HP Ultra is a fully synthetic 2-cycle engine oil specially suited for high performance chain saws and power tools. This oil has outstanding engine cleaning characteristics, plus “ultra” superior lubricating qualities in comparison to other 2-cycle engine oils. This oil is biodegradable, degrading by 80% in 21 days.

 

[WarDamnEagle]

I don't think that means that it will biodegrade mixed with gasoline.

All refined oils are somewhat biodegradable. I'm not sure why they would even mention it as I don't think many people are going to pour one of those little bottles onto the ground. Sounds to me like they are just trying to tout their enviornmental friendliness which is sort of ironic considering it is primarily a chainsaw company.

 

[D'Animal]

and evapratory emmissions.

Sounds to me like they are just trying to tout their enviornmental friendliness which is sort of ironic considering it is primarily a chainsaw company.

Not all of the oil is burned in the combustion chamber. If it were, the engine would overheat and seize. So what happens to the oil vapor that comes out the exhaust? Does it lay around like MTBE and end up in the ground water?

If you look at the water in most marinas, you will notice an oily film on the water. Most all bio-synthetics will not cause this.

 

[jeffro109]

try to find ethanol free gas if you can, supposed to make a difference from what the repair guys all tell me. I have a place nearby that sells it, so I run it in my 2cycle stuff with good quality mix oil and a touch of sea foam in the mix gas too, works like a stabilizer and is cleaning all the old crap out of my engines too.

 

[Jimmy B]

A little off topic but question for D'Animal,we run 1/5 scale rc buggies(hpi baja) with 23-30cc 2-cycle motors in them.Basically a weedeater motor.Alot of guys are running Coleman camping fuel instead of pump gas with no problems,reason,it does not smell if living in apartments,storing in house,it does not go bad over winter(varnish etc)This fuel cannot be used in 4-cycles.Local lawn and garden shop has a similar product,I recall manufactured in Europe(Germany perhaps)both available for 2 and 4 cycle engines now but you cannot interchange them,not sure why.
Just curious if you have any experience with this??

Thanks James..

 

[D'Animal]

It is a a very pure fuel. The diaphragms in the carburetor and the fuel line may not like it but the engine will. You will more than likely have to change the fuel lines to Tygon.

 

[e9999]

try to find ethanol free gas if you can, supposed to make a difference from what the repair guys all tell me. I have a place nearby that sells it, so I run it in my 2cycle stuff with good quality mix oil and a touch of sea foam in the mix gas too, works like a stabilizer and is cleaning all the old crap out of my engines too.

Sea Foam eh? mmm....

anybody else?

 

[Chang-kuao-lo]

speaking from experience with 2 stroke motorcycles, high test is only needed for higher compression engines to prevent detonation, burn a hole in the piston. etoh blended gas is hard on the crankcase seals, so i'm using shell high test because i have a high compression engine, and that particular fuel has no ethanol. not sure if the octane counteracts the negative effects of etoh, or if that high test just has less or no ethanol in general.

motul or amsoil sythetic 2-stroke oil seem to burn about the cleanest.

 

[e9999]

IIRC ethanol has a very octane rating. Is it used to boost octane rating in some fuels as well as to oxygenate them? Maybe there might be more ethanol in 91 than in 87 in some cases?

 

[Chang-kuao-lo]

...not sure. all i know is that shell vpower high test is etoh free around these parts. that may vary state to state.
i'd be willing to bet that dyed "off-road" gasoline has no ethanol.