So, yesterday I went into my local John Deere dealership to get a new belt for my STX46. Kohler Command 14 motor.

For some dumb reason I asked about the type of fuel I should be burning in it. Figured now that I’ve had it since 1995, this would be a good time to get it right.

The guy at the parts counter tells me that I should always buy premium unleaded for it. Well - That seemed odd, as it’s been cutting the grass around my hangar (now home) for the last 14 years just fine on regular unleaded.

He tells me that “due to evaporation”, that after one week, premium is as good as mid-range and that after two weeks its only as good as regular unleaded. Then after three weeks is isn’t worth a darn.
Heck, I’ve run regular unleaded fuel in it that has sat in a can for over a month and it ran just fine.

I’m thinking he must be talking about the evaporation of the ethanol that’s in fuel these days.

I think I know a little about the premium fuels being made for higher compression engines. They burn slower, right? Less energy by volume than regular unleaded.(?) It’s a ping-thing. My autos/trucks run on what they tell me to run them on. That's about as far into it as I've ever gotten.

I think there was a thread on this issue not too long ago. That’s why what he was saying hit me wrong.

Most everything I own runs on 100ll-AvGas or Jet-A.
I know a bit about those fuels and all the stuff that John and Darby add to them for competitions, running in the V1650, Biobor biocides for stored JetA, etc..
But I’m not up on the finer properties of unleaded fuels.

Does what this guy told me make any sense to any of you?
If so – Teach me something.


Thanks for your time -

Cheers -

Shelby

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1980 300D - Veggie Burner !

That Kohler is a low compression engine and there's no reason to run premium in it. I have never heard of the evaporation thing either.

The only thing I ever do is put a quantity of fuel stabilizer in the gas can every time I fill it up. That way, the gas that's in the can or in any of the machines is stabilized for a good long time.

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-Evan


Benz Fleet:
1968 UNIMOG 404.114
1998 E300
2008 E63


Non-Benz Fleet:
1992 Aerostar
1993 MR2
2000 F250

The only thing I can say is I have a little Murry mower and I fill it with the cheapest gas I can find and if its the last time I mow before the winter then the gas stays in there until I use it in the spring and I have no problems starting and running it.

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1983 300SD
200000miles

Back when I was in high school, I got a summer job testing prototype lawn mowers for Snapper. We ran the mowers on AvGas. It was explained to me that the engine durability was tested seperately and we were mostly concerned with the durability of the rest of the mower. The AvGas supposedly was to keep the carbs from gumming up.

That much being said, everyone else I know runs their small gas engines on regular and it seems to work just fine.

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Whoever said there's nothing more expensive than a cheap Mercedes never had a cheap Jaguar.

83 300D Turbo with manual conversion, early W126 vented front rotors and H4 headlights 401,xxx miles
08 Suzuki GSX-R600 M4 Slip-on 26,xxx miles
88 Jaguar XJS V12 94,xxx miles. Work in progress.
99 Mazda Miata 183,xxx miles.

We run our mower on premium, as we usually fill the gas can at the same time we are filling one of the cars...

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-Justin

91 560 SEC AMG - other dogs dd
01 Honda S2000 - dogs dd
07 MB ML320 CDI - dd
16 Lexus IS250 - wifes dd

it's automatic.

Shel- the guy who gave you the info probably has a 427 with a 411 posi-rear-end on his John Deere....

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"It's normal for these things to empty your wallet and break your heart in the process."
2012 SLK 350
1987 420 SEL

Sorry but IMHO, Deere counter people can't fog a mirror. Show me some data on that evaporation BS. Otherwise use some Stabil for long term storage, the rest of what he said is purely anecdotal.

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Never a dull moment at Berry Hill Farm.

There was a thread recently that said something like "fuel degrades after so many days..." but I think that referred to separation or formation of water, organic compounds, etc, and did not refer to octane rating.

I've got a finicky Honda mower that explicitly says DO NOT use premium in the manual. It also doesn't like month old gas, but I think that has more to do with a slightly corroded fuel bowl more than the fuel itself.

I'll agree with all of that.

As for the counter guys: I always look up my parts needs online and go in with the part numbers of what I want. I’ve told them what I needed and they’d order the wrong part in the past. Not playing that game anymore.

As for the fuel issue. I wasn’t buying most of what he was saying. It just didn’t make sense to me. Hence, this thread.
Thought I’d get some views from you folks that know more than I.
For that – My thanks to you all.

I’ve always done the Sta-Bil treatment with my mowers, tiller, edger, etc fuels. Seems to work good. A must for the Stihl 2 cycle toys. John is a USFS Class B Sawyer Certification instructor. He and I go head to head on occasion for fun when we have to fall a tree around here. He has some wicked custom Stihl chainsaws in his arsenal. Fun toys !! He swears by the stuff for fuel mixes he lets stand over a couple of weeks.


You getting much of this rain down there, Randy?

I’ve had a few calls from the DFW area press wanting me to get them up with the morning light to cover areas north and west of FW. We’ll see what the weather is doing by then. But it sure sounds like a bit of flooding going on.

Thanks again to you all for your replies.

Cheers –

Shelby

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1980 300D - Veggie Burner !

My lawn mower runs on diesel

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-Typos courtesy of my mobile phone.

Must have.

Next time, I'll show up with my 330/500 and 3.31 rear-end and see if he'll get his Deere out and play.

- Shelby

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1980 300D - Veggie Burner !

We've always run our lawn mowers and power washer on regular unleaded. When we put the mowers away for the season we just run them out of fuel. However in a bit of irony, when we winterized the power washer once the fuel stabilizer is was ended up clogging the carburetor

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1982 300GD Carmine Red (DB3535) Cabriolet Parting Out
1990 300SEL Smoke Silver (Parting out)
1991 350SDL Blackberry Metallic (481)

"The thing is Bob, its not that I'm lazy...its that I just don't care."

J & D do too. But then...y'alls yards are bigger than mine.

They mow the strip with a "batwing" (?) behind a Case 95c.
Looks kind of boring to me though.


-Shelby

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1980 300D - Veggie Burner !

New fuels are pretty crappy and start to break down after a few weeks. On all the little equipment, ie cut off saws, road saws, mowers, blowers, trimmers, compactors, etc we run regular gas with Sta-Bil. This keeps them running good if they sit for a few weeks or months.

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2006 CL500
1969 280SE
2023 Ram 1500
2026 Genesis GV70
2007 Tiara 3200

Not yet. Looks like the bottom may fall out around 2:00am.

Last week when this happened, SWMBO had driven her car back here to the cabin (against my instructions) so, it sat there for over a week. She had to fold up and drive Dad's Escort ZX2 to Austin . I got her car out this last Monday...since then, I've spread about 30yds of road base/stabilizer on the road to the cabin. It might be passable in heavy rain but I'd sure like to get some gravel on it first.

Road maintenance work, loading and hauling steers, making price lists for beef....sometimes there's not enough of me to go around. I need a clone.

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Never a dull moment at Berry Hill Farm.