Premium grade fuel in small engines

[Chas B. Wolfson, SASS #11104]

 I have read several articles regarding using premium grade fuel in small engines.  It seems the lower flashpoint temperature helps to run the engine at an overall lower temperature.  Also, many premium grades contain higher/better detergent packages which I would think a beneficial thing.  Especially where non ethanol fuel cannot be purchased.

Anyone here have any experience regarding this?

Thanks,

Chas B 

And yes, already use Chevron Techron and Marvel Mystery Oil

 

 

 

 

 

 

 

 

Edited February 16 by Chas B. Wolfson, SASS #11104

[Cypress Sun]

Non ethanol fuel is a must for use in small engines for me. 

 

I haven't seen any options on selecting different grades of non ethanol fuel. 

 

[Abilene Slim SASS 81783]

I read many years ago that if an engine wasn’t specifically designed to take advantage of premium gas, buying it was a waste of money. 
 

My walk-behind lawn mower is 25 years old and my 2-stroke blower, string trimmer and small garden tiller are even older. All were designed for 87 octane gas. 
 

Premium fuel has a higher, not lower flashpoint. Higher octane rating means it resists detonation from the increased heat resulting from high compression. 

[Rip Snorter]

Ethanol is the issue - at least here, Premium is alcohol free.

[Chas B. Wolfson, SASS #11104]

 Everything in the Phoenix metro is ethanol including premium.

 

[Finagler 6853 Life]

Racing fuel is non-ethanol but runs 100 octane to 110.  Pretty pricy also.  I think it runs close to $10/gallon.  They sell a pre-mix in a can but that is pricy as well.  I've seen some mechanics online and they curse the stuff.  Ask your small engine guy.  They should know which stations offer a non-ethanol fuel.  I've used premium/non-ethanol for years.  It is the only way to go.  Most ATV/UTV guys use non-ethanol.  They should be able to tell you where to find it.  Good luck.

[Abilene Slim SASS 81783]

Can’t buy non-ethanol fuel here. I don’t know why anyone would need to, outside of specific uses like racing. 
 

IMO, it’s a total waste of money for a small, low-tech engine like a lawnmower designed for cheap, low octane gas. 

[Rip Snorter]

Whatever works for you - what I do works for me! 

[Cypress Sun]

1 hour ago, Abilene Slim SASS 81783 said:

Can’t buy non-ethanol fuel here. I don’t know why anyone would need to, outside of specific uses like racing. 
 

IMO, it’s a total waste of money for a small, low-tech engine like a lawnmower designed for cheap, low octane gas. 

 

It isn't about the engine's performance using cheap, low octane gas with a ethanol filler. The engine will run just fine with the stuff. It's the long-term effects that the ethanol takes on the motor's components, namely gaskets, fuel delivery hoses, carburetor, diaphragms and the like.

Edited February 16 by Cypress Sun
damn otto

[Abilene Slim SASS 81783]

4 minutes ago, Cypress Sun said:

 

It isn't about the engine's performance using cheap, low octane gas with a ethanol filler. The engine will run just fine with the stuff. It's the long-term effects that the ethanol takes on the motor's components, namely gaskets, fuel delivery hoses, carbonator, diaphragms and the like.

My lawn equipment has been running great on the stuff for over 25 years. Those things deteriorate over time regardless. I'm not worried about it.

[Vail Vigilante]

Premium is a must for air-cooled engines. Including my Harley.

 

 

[sassnetguy50]

1 hour ago, Abilene Slim SASS 81783 said:

My lawn equipment has been running great on the stuff for over 25 years. Those things deteriorate over time regardless. I'm not worried about it.

If your state only has ethanol blends, your stores are going to sell ethanol rated equipment.   That is not the case everywhere.   

[Pat Riot]

At first I thought you meant small engines as in cars and motorcycles, like 2000cc and under. 
I run 93 octane in my Miata and my Kawasaki Versys 650. They aren’t made to run on 87 octane. Minimum is 91.

 

I remember a small engine repair guy telling me that higher octane gas is better for small engines, though I cannot remember his reasons. 

[watab kid]

cant find it at all stations here but i run only non-alcohol in all my small engines including my boat [which is not really small , i run the higher octane in my suburban and my wife runs that in her oudi as the manual recommends , we have had very few engine related repairs mostly sensors or filters that you expect , 

[Abilene Slim SASS 81783]

21 minutes ago, sassnetguy50 said:

If your state only has ethanol blends, your stores are going to sell ethanol rated equipment.   That is not the case everywhere.   

So you’re saying that the fuel line hose on my Honda mower engine, is made from a different material than an engine bought in a state where non-ethanol gas is available? And that Honda and replacement parts mfrs keep tabs on the different markets where gasoline blends vary? That would be a logistical nightmare. 
 

We’re talking lawnmower equipment here, not flex fuel autos. 

[Abilene Slim SASS 81783]

6 minutes ago, Pat Riot said:

At first I thought you meant small engines as in cars and motorcycles, like 2000cc and under. 
I run 93 octane in my Miata and my Kawasaki Versys 650. They aren’t made to run on 87 octane. Minimum is 91.

 

I remember a small engine repair guy telling me that higher octane gas is better for small engines, though I cannot remember his reasons. 

Yup, your Miata and Kawasaki need the higher octane in order to run properly. Note that it’s 91, which is the highest octane available in many markets. If they required higher octane, they’d lose sales for lack of available fuel. 

[Pat Riot]

2 minutes ago, Abilene Slim SASS 81783 said:

Yup, your Miata and Kawasaki need the higher octane in order to run properly. Note that it’s 91, which is the highest octane available in many markets. If they required higher octane, they’d lose sales for lack of available fuel. 

Here in WV we have 87, 89 or 93. In CA & OR the highest octane was 91. 
This is a photo of the Exxon pump at the station just down the road from me. 

[Pat Riot]

Pennsylvania also has 93 octane gas. 
 

[Chas B. Wolfson, SASS #11104]

 By small engines I meant lawnmower, generators and golf cart.  My mistake for not being more specific.

[John Barleycorn, SASS #76982]

To find ethanol free gas stations, use this website. Pure-gas.org

Edited February 17 by John Barleycorn, SASS #76982

[Abilene Slim SASS 81783]

7 minutes ago, Pat Riot said:

Pennsylvania also has 93 octane gas. 
 

I’m old enough to remember when Sunoco, a brand long gone from our market, had 101 octane gas for those behemoth engines in the late 60s. All we can get here is 87, 89 and 91. In neighboring Colorado the low end is 85. Not sure if 91 is available. I believe the 85 octane is 20 percent ethanol, vs 10 percent in 87. 
 

The only 100 octane gas I’m aware of now is the avgas I put in the planes I flew. 
 

Edited February 16 by Abilene Slim SASS 81783

[Abilene Slim SASS 81783]

14 minutes ago, Pat Riot said:

Here in WV we have 87, 89 or 93. In CA & OR the highest octane was 91. 
This is a photo of the Exxon pump at the station just down the road from me. 

Pat, I can’t make out the text above the octane rating on the fuel grade buttons. Can you make them out and share? 

[Pat Riot]

3 minutes ago, Abilene Slim SASS 81783 said:

I’m old enough to remember when Sunoco, a brand long gone from our market, had 101 octane gas for those behemoth engines in the late 60s. 
 

The only 100 octane gas I’m aware of now is the avgas I put in the planes I flew. 

Sunoco has 87, 89 and 93 unleaded. They also have non-ethanol fuel at a Sunoco near me but I cannot recall the octane number. It’s for off road vehicles only. If they see you putting it in your car they will shut the pump off. 

[Assassin]

I only use ethanol free, which is 91 octane here in Wyoming. Might have something to do with elevation and extreme temerature changes (-20 up to 90), 6600' here at my place. 4 wheeler, SxS's, mowers, tractors, motorcycles, chainsaws, weed eaters, log splitter, sawmill, etc all run better without ethanol. Some equipment might sit for six months between seasons. I try to run equipment dry before storing. Well worth the extra 50 cents a gallon.

[The Original Lumpy Gritz]

Premium is all I use in any air-cooled engine and my 1985 Jeep cj7 with 258 6cyl.

[Michigan Slim]

I only run REC90 in my two stroke engines. No ethanal! 

[El Chapo]

I try to buy ethanol free for my vehicles that have carburetors, whether they are motorcycles, leaf blowers, lawnmowers, or even my generator.  There is one station here that has it, and it's 91 only.  If I could buy 87 octane pure gasoline for those engines, I would, because none of them require or benefit from premium.

 

My Harley-Davidsons, I'll fill them at that station if I'm nearby but I usually don't go out of the way to do that.  They get ridden a lot and are fuel injected, so I am not really worried about it.  The big bike does ping a lot less in hot weather with the pure gasoline though so in the summer, I go out of my way to get pure gasoline for it when it's 100 degrees.  Even with stock timing, I don't like hearing detonation, even if it's in an amount that is likely harmless.  I do run 91 in them 100% of the time, as that is what they call for.

 

To answer the original question: I do not believe you're achieving any benefit from running premium fuel in a lawnmower.  It has less energy and really the only harm is to your pocketbook, it will have slightly less power on 91 than 87, but not something you're ever going to notice.

Edited February 18 by El Chapo

[sassnetguy50]

On 2/16/2026 at 3:11 PM, Abilene Slim SASS 81783 said:

So you’re saying that the fuel line hose on my Honda mower engine, is made from a different material than an engine bought in a state where non-ethanol gas is available? And that Honda and replacement parts mfrs keep tabs on the different markets where gasoline blends vary? That would be a logistical nightmare. 
 

We’re talking lawnmower equipment here, not flex fuel autos. 

I do not know if Honda switched their full line to E15 safe or not, obviously your model is.  Some brands still make both.  The gasoline only engines are a different model number than E15 safe engines.  It is no different than having to order parts for a 49 state machine versus a California machine or a flat land vs high altitude model.  Bottom line, E15 safe gaskets and lines cost more and manufacturers look at every penny.  EPA requires automobiles to be E15 safe but not small engines.  

[sassnetguy50]

10 hours ago, El Chapo said:

I try to buy ethanol free for my vehicles that have carburetors, whether they are motorcycles, leaf blowers, lawnmowers, or even my generator.  There is one station here that has it, and it's 91 only.  If I could buy 87 octane pure gasoline for those engines, I would, because none of them require or benefit from premium.

 

My Harley-Davidsons, I'll fill them at that station if I'm nearby but I usually don't go out of the way to do that.  They get ridden a lot and are fuel injected, so I am not really worried about it.  The big bike does ping a lot less in hot weather with the pure gasoline though so in the summer, I go out of my way to get pure gasoline for it when it's 100 degrees.  Even with stock timing, I don't like hearing detonation, even if it's in an amount that is likely harmless.  I do run 91 in them 100% of the time, as that is what they call for.

 

To answer the original question: I do not believe you're achieving any benefit from running premium fuel in a lawnmower.  It has less energy and really the only harm is to your pocketbook, it will have slightly less power on 91 than 87, but not something you're ever going to notice.

The power from the fuel has to do with the composition, not the octane.  Yes, higher octane has greater ping resistance, along with other factors.  Ethanol blends will have less energy per volume than gasoline assuming the detergent and any other fillers are the same.  The stoich ratios are also different between gasoline and ethanol, some EFI can compensate for this, carburetors do not.  

[Cypress Sun]

The problem with ethanol fillers and small 4 cycle and 2 cycle motors is not performance. It's the occasional usage in an engine powering such devices as a weed eater, chainsaw, generator, blower or the like and then letting the device sit for months. 

 

It's a slowly corrosive filler folks, all it is. 

[PowderRiverCowboy]

On 2/16/2026 at 10:38 AM, Abilene Slim SASS 81783 said:

Can’t buy non-ethanol fuel here. I don’t know why anyone would need to, outside of specific uses like racing. 
 

IMO, it’s a total waste of money for a small, low-tech engine like a lawnmower designed for cheap, low octane gas. 

 

Never say never  

https://www.pure-gas.org/

[Tye Riverman, SASS #41433]

Non ethanol for anything the gas will sit in any length of time and add stablizer.  If you have to use ethanol gas use a top tier brand with the added detergent package and again add stablizer for longer life.  Octane for any engine should be in accordance with the manufacturers recommendations.   Most small engines do not have the computer based variable timing like some of the new vehicles that can to accomodate different octanes.  High compression engines usually need higher octane.   This is just a snapshot of info.  A lot more out there on the internet.

 

I run top tier in my truck and cars, but non ethanol in my smaller engines and I have a bunch of them that tend to sit for long periods without regular use.  I was also a mechanic in my first career so have a bit of experience.

 

A quick diddy, I let me son use my honda self propelled mower.  He put ethanol gas in it, got a riding mower, and let it sit for 2 years.  The carb is a mess and I may have to replace it.  Ethanol dries into a hard gum if you let it sit.  If you use it on a regular basis you may OK.

 

My view from the saddle and hope this helps,

YMMV

Tye

[El Chapo]

1 hour ago, sassnetguy50 said:

The power from the fuel has to do with the composition, not the octane.  Yes, higher octane has greater ping resistance, along with other factors.  Ethanol blends will have less energy per volume than gasoline assuming the detergent and any other fillers are the same.  The stoich ratios are also different between gasoline and ethanol, some EFI can compensate for this, carburetors do not.  

 

Making gasoline with higher octane means requires adding things to the gasoline that necessarily reduce the BTUs per gallon.  A gallon of premium has less energy than a gallon of regular.  Putting premium in an engine that does not need premium will produce a reduction in output as a result, it's simple physics.

[Chickasaw Bill SASS #70001]

the only 100% gas , I can get here is 91 ?prem 

 

 all I run in everythng 

 

 but , you do need to pump a couple of gal in the truck before putting in cans for small engines / storage 

 

 ya got no clue as to what was pumped , before ya hit the pump 

 

   CB 

[Warden Callaway]

We blew up two engines running 87 octane with ethanol.  Had a Husqvarna chainsaw that every 6 months it would not start.  Take to repair and it would have a hole in the gasline.  We now run 91 proof non-ethanol in all our small engines.