Octane rating of gasoline is often misunderstood. Gasoline is composed of different compositions of hydrocarbons produced by distilling crude oil at different temperatures to obtain these fractions. Some of the longer molecules are converted to smaller chains of hydrocarbons by "cracking" the double bonds or some of the shorter chained fractions are made longer by "isomerization." These fractions are mixed and tested in a knock engine that varies compression and compares the knocking of your mixture against a known fraction called isooctane that has a knock value of 100. Knocking is caused by pre-ignition of the fuel from the heat of compression, before the spark plug fires.
Thus, since small engines are not high compression engines, knocking should not be an issue regardless of the octane rating used. Also mixing your gasolines just creates your own mixture with your own octane number. Running engines on octane ratings higher than necessary to prevent knocking does not give more power as commonly thought.
You can learn more here: http://chemistry.about.com/cs/howthingswork/a/aa070401a.htm
-Lee
On May 26, 2012, at 7:45 AM, Doug Kalmer wrote:
The ethanol in most gas is what degrades fuel lines and carb parts, avoid it for small engines and older engines. If you use the recommended octane, going to a higher grade will not harm the engine, but it just costs more. Mixing octanes is OK. DougHigher octane gas for lawn equipment
Posted by: "subprong" subprong@gmail.com subprong
Date: Fri May 25, 2012 11:09 am ((PDT))
My 2 stroke blower suggests 89 octane gas. Is there any reason a
higher octane gas will harm or disrupt a piece of lawn equipment? I
was thinking about getting the higher octane for a 2-cycle trimmer and
an older 4-cycle mower as well. Also, can different octanes be mixed?
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