octane and ethanol

AndySKane

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The Kawasaki engine on my Ferris mower recommends minimum of 87 octane and no more than 10% ethanol. I don't know of any ethanol free gas sellers around me and don't plan to look for them.

What are the thoughts on harm or benefit to the engine if a higher octane is run? I know running a lower octane than specified will hurt an engine but I've read that running a higher octane will either make no difference because the engine's compression level can't utilize it or that it is harmful in that it causes run on after shutoff.

Would a higher octane offset any potential negative effects of the ethanol?

How about additives to offset any negative effects of ethanol. I've read where there are such products but I've also heard them described as snake oil.

Perhaps it's best just to run it with 10% ethanol 87 octane gas as recommended by the engine maker.
What are your thoughts and what is everyone else doing?
 

reynoldston

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The engine was designed to run with that fuel so why would you want to run anything else?
 

BKBrown

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Contrary to popular belief, higher octane burns slower. If Kawasaki recommends no more than 10% ethanol they must believe that any more can/will harm the engine (or it won't run as well on more). Sta-Bil makes a "marine grade" (blue) formula that is designed to offset the effects of ethanol fuel (my guess is they say marine grade because most engines used in boats/watercraft are affected more by the ethanol). I use it at recommended strength in the gas for my tractor and add it to the gas in car and truck most of the time. I have found it in larger containers and less expensive at Tractor Supply. If the engine runs well on 87 octane, don't waste $ on higher levels. JUST MHO.
 
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AndySKane

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The engine was designed to run with that fuel so why would you want to run anything else?

Often times manufacturers make compomises to accomodate what is most readily available but may not actually be best for the engine.

Primarily I ask this because the manual says a minimum of 87 octane and no more than 10% ethanol. so the first question is would a minimum of 89 or 91 octane be better. The manual did not specifically state not to use a higher minimum octane.

Secondly ethanol is not the first choice for engine fuel and was forced upon us for other than engine efficiency reasons. I have read of the negative effects of ethanol and was wondering if any additives are worth the money to try to offset them.
 

Jetblast

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Higher octane ratings are to prevent detonation with higher compression ratios, and in cars with knock (detonation) sensors, it's to prevent a loss of performance caused by the electronic ignition system retarding itself to prevent knocking. I don't think very many small engines have knock sensors, so it's the detonation we're worried about. If you don't hear knocking, you're good to go.

If your engine is rated for 87 octane, any higher octane would be a complete waste of money despite a decades-long scam marketing effort by the oil companies to convince us otherwise. Higher octane burns more slowly to ease detonation in high compression engines, but in every other regard it's exactly the same fuel. It simply burns more slowly and cannot offset ethanol in any way.

Ethanol is no problem to a newer engine. Ethanol has solvent properties so it can erode non-metal parts in the fuel delivery system in older engines, but newer engines use materials that are made to withstand it. Either way though, ethanol fuels degrade more quickly and have greater hygroscopic properties, so they need to be used up fairly quickly especially in extreme humidity environments, or treated with a fuel stabilizer like STA-BIL. I don't bother with STA-BIL during mowing season, but I do use it for winter storage and for my rarely used generator. Works great, no problems yet.
 
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reynoldston

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I have about 700 hr. on my ferris with a kohler engine and all I have ever used is 87 octane and never looked at how much ethanol it has in it. All I know it is the cheapest gas I can buy. The engine has never had a problim yet and runs just fine on it. I think that will be the lease of your worries on your Ferris. Just keep all your maintenence up on it and you will have one of the best mowes made.
 

oldyellr

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While many years ago ethanol in gas affected some of the plastic and rubber parts in engine fuel systems, that is no longer the case today. All gasoline today contains some ethanol and engines are made to live with it. One drawback of ethanol in gas is that it absorbs water, so there is more likelihood of corrosion in the tank and fuel system. However, ethanol is one of the components that raises octane and is now used instead of lead which is now taboo. Using ethanol in motor fuel is also politically correct because it comes from sustainable sources and not those crooks that own the oil wells. However, its heavily subsidized by our tax dollars and indirectly raises the price of our food.
 

Ric

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If you have a problem with ethanol try using a Top Tier Gas. They use an additive to offset any effects of ethanol. Most all manuals will recommend a minimum of 87 octane and no more than 10% ethanol, That doesn't mean you can't run higher octane, it will not hurt the mower engine.

According to its marketers, all vehicles will benefit from using Top Tier Detergent Gasoline over gasoline meeting the basic EPA standard. Deposits will reputedly be minimized on fuel injectors, intake valves, and combustion chambers.
New vehicles will supposedly benefit by keeping their engine clean and running optimally, older vehicles may benefit with increased engine performance and prolonged vehicle life.
Using this gas is purported to have the following benefits over gasoline's just meeting the EPA standard:

  • Improved fuel efficiency
  • Reduced driving upsets (rough idle, stalling and surge)
  • Improved acceleration
  • Increased engine power
  • Reduced emissions
If you check some of the manuals say on Stihl Trimmers, blowers and such they all recommend 89 and higher octane gas with no more than 10% ethanol. I personally use nothing less than 89 in all my equipment mowers included, Exxon Mobil.
 

Jetblast

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I just looked up "Top Tier Gasoline". Wow, that new oil lobby campaign is a new one on me, but it's the same old scam. Thanks for bringing it forward.

Like I said earlier in this thread, "If your engine is rated for 87 octane, any higher octane would be a complete waste of money despite a decades-long scam marketing effort by the oil companies to convince us otherwise. Higher octane burns more slowly to ease detonation in high compression engines, but in every other regard it's exactly the same fuel. It simply burns more slowly and cannot offset ethanol in any way."

I don't see any credible evidence from the oil companies with their "Top Tier" campaign to offset that idea, but I'm eager to listen.
 
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Ric

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I just looked up "Top Tier Gasoline". Wow, that new oil lobby campaign is a new one on me, but it's the same old scam. Thanks for bringing it forward.

Like I said earlier in this thread, "If your engine is rated for 87 octane, any higher octane would be a complete waste of money despite a decades-long scam marketing effort by the oil companies to convince us otherwise. Higher octane burns more slowly to ease detonation in high compression engines, but in every other regard it's exactly the same fuel. It simply burns more slowly and cannot offset ethanol in any way."

I don't see any credible evidence from the oil companies with their "Top Tier" campaign to offset that idea, but I'm eager to listen.


You can believe what you want but I used the 87 minimal standard gas crap in my mowers and equipment when I first purchased them and they ran yes and my hand held equipment ran like the gas I was buying...crap. I switched to a Top Tier gas and the difference is day and night. Same with my car and Truck, they start better, run better and I get better gas mileage with an 87 octane from a Top Tier vs the minimal standard gas.

If what you say is true and that this gas thing is know more than a scam why is it that most vehicles manage better gas mileage and produce better performance running a Top Tier Gas than the minimal standard gas. If what you say is true why doesn't Nascar just burn the minimal standard gas in there cars if there is no difference?

Top Tier Detergent Gasoline was developed to increase the level of detergent additive in gasoline. The EPA requires that all gasoline sold in the U.S. contain a detergent additive. However, the requirement is minimal and in many cases, it's not sufficient to keep engines clean. In order to meet Top Tier Detergent Gasoline standards, a higher level of detergent is needed than what is required by the EPA. Has nothing to do with octane levels. All octane levels at a Top Tier gas station have a higher level of detergent.
 
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