Is it better to run out of gas periodically vs topping off the tank before each use?

I don't do anything special to my OPE engines for winter. I always use ethanol-free gas, and everything runs every spring. My main mower is a Cub Cadet Pro Z, which has dual fuel tanks. I let one run completely empty before switching tanks. This keeps fuel from ever going bad. The fuel in each tank is always less than 2 months old. The engine will start sputtering, and if you're paying attention, a quick tank swap will allow it to keep running. This is the 4th season I've had this mower, and this is how I've always done it, and I've not had any problems with it. Well, any problems related to this practice.
 
I’ve always parked my mowers with E10 in the unheated garage for the winter. Always started easy next spring.

The Honda engine is the only one I did anything special for. Carburetor needed to be run dry to restart in 2 weeks or 4 months. Gas in tank was fine.

E10 in my zero-turn is about 6 months old.
 
Hello Folks,

Keeping equipment "at the ready" is something I had instilled in me year ago.

I grew up in the mountains of Virginia and recall when we would drain or siphon/pump all the fuel out of equipment for our cars and trucks then run the equipment carburetors dry and store them for the long Fall/ Winter.

The small engine equipment oil only got changed if it was starting to turn black from carbon blowby. We had mostly antique Clinton and Tecumseh along with cast-iron Briggs and Stratton powered equipment. Aluminum small engine equipment was just becoming popular. We seldom had running issues except for the occasional worn-out contact points.

Now, I'm here in Texas (40+ years) and I keep the equipment fuel tanks full of non-Ethanol fuel and change the oils in the early Winter and late Spring as time permits me. Down here in South Texas, the equipment seldom gets stored or shut down for any significant length of time. I have limited storage, so I only rotate out a few bulk gallons of oil and fuel without them sitting around having birthdays.

My emergency generators get run once a month for 30-60 minutes regardless of need and I transfer the fuel in them to my mowers in the Spring, so the generators always have the freshest fuel in them. (My 15KW Generac portable has a 16-gallon fuel tank, and the 5KW Storm responder has a 7-gallon fuel tank). I also keep a 16-gallon boat tank 90% full of treated fuel during the Winter stored under an outside overhang. My smaller generator is also setup to run on Propane, so I have 5-20lb (about 4-gal. each) bottles that I rotate out as I use them.

For two-stroke stuff, I mix the oil/fuel as I need it, then empty the 2-stroke tanks when done using them and keep the fuel in a tightly sealed 1-gallon metal can. I do not try to run the carburetors on them dry because the diaphragms will stiffen up and crack.

For me, I keep the fuel tanks topped off and the oil levels full year-round. Even though I keep fuel constantly renewed, I still like to use a fuel stabilizer additive as good "future insurance" in case I become incapacitated for a period of time.

For my customers who insist on using regular E-10 fuel I advise them to use Seafoam, Star-Tron, Ethanol shield or the "Blue" Marine Stabil fuel stabilizer. I have found that the heat down here affects the "Red" Stabil. Of course, some of these same customers think treated fuel will last for years (LOL).

I like repeat business, but not for the same reasons year after year.

Even as a small engine "repair guy" I still have trouble with my own equipment from time to time, but I do my best to minimize the severity.
 
What I do…don’t know if it is correct. Put fuel stabilizer in the fill can on every fill up. Top off the mower after each cut. Ethanol free is not available in my area. Just park it in the fall. Seems fine for the 4-5 months it sits… Small engine equipment that sits year round is filled with VP 4 cycle fuel. It’s about $80 for a 5 gallon pail and it last a few years in the overseeder, pressure washer, snow blower and aerator.
 
I always, if possible, install a fuel shutoff valve.
I always shutoff the fuel and run the carburetor dry and finally turn off the key. I’ve had too many, over the past 30 years, carburetor needle and seats fail and dump the fuel into the oil.

Once you have fuel in the oil bad things happen!

I’m now installing battery disconnects to my OPE-Outdoor Power Equipment.

My procedure now is turn on the fuel shutoff valve, screw in the battery disconnect, choke the engine and go.

I love how some engines have a fuel bowl drain. If I know I’m putting the equipment up for off season then I try to drain the bowl too.

I NEVER leave an engine without oil. Ex-wife went and cranked up my mower to “help”. I think you know how this ended?

I hope my procedure helps answer your original question?

Drew
 
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I think the OP is asking a question that will take "intimate" knowledge of what is happening or happened inside an engine. It seems to me that there are some hints or clues in the comments above. But I suggest that this question might get an acceptable answer on a forum aimed at engine tear down and analysis. :)
 
The original question was should the OP keep the fuel tank full, or should he wait until he needs to use the equipment to fill it. It's been my understanding for years that a full tank leaves very little room for moisture-laden air, and thus should be kept full. I use only ethanol-free gasoline in my small engines, chain saw, weed eater, leaf blowers, etc. My chain saw is 20 years old and gets used a lot in fall and winter, and I have never had an issue with it. Same with the weed eater, 22 years old, never a problem. Both are Stihl FWIW, and I use only Stihl synthetic oil. But, in both I fill the tanks after every use. This goes for summer or winter equipment. I've never had a fuel related problem with any of my engines. I'd run ethanol-free in my vehicles if I could afford it.

Another reason to always keep the tank full is simply have it ready to go when you need it. If the power fails, I don't want to have to take the time to fuel up the generator. I want it ready to start at a moment's notice.

Oil...I would never leave an engine without oil for any reason. While almost no one has access to my equipment but me, I don't want to have to make an admission sometime that I started an engine with no oil in it. IMO there is never a reason to leave an engine without oil.

Just as an anecdote, I had a Ford 3000 diesel tractor that blew the radiator in 2006. I had plenty of tractors and little time, so I didn't get around to fixing it for 16 years. When I retired I tackled that job. The engine had set for 16 years without moving, barely even touched. I changed the oil, put a new battery in it, and it started up the first try. Same diesel fuel that had been in it when I parked it. The fuel tank had been filled when I parked it. Take that for what it's worth.
 
I leave gas in my engines and never drain. Some equipment (such as my standby generator) sit for over a year between uses.

One trick I use, is to add "Sea Foam" and "Stab-bil" to my gas can before filling with gas at station. Mix a half gallon, stop and swish container to mix chemicals with gas, the continue to fill up. (Will buy non-Ethanol gas when I can, but currently running Ethanol gas as the good stuff is getting harder to find.)

Never have any problems starting or running even though gas has sat in equipment for a year or more.
 
enigma-2 said:
I leave gas in my engines and never drain. Some equipment (such as my standby generator) sit for over a year between uses.

One trick I use, is to add "Sea Foam" and "Stab-bil" to my gas can before filling with gas at station. Mix a half gallon, stop and swish container to mix chemicals with gas, the continue to fill up. (Will buy non-Ethanol gas when I can, but currently running Ethanol gas as the good stuff is getting harder to find.)

Never have any problems starting or running even though gas has sat in equipment for a year or more.
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Same here, never had a problem. Yet. I just learned from my son that our local Walmart (Murphy's) gas station has completely replaced their Ethanol-Free pumps with Flex-Fuel. Dangit! So, I guess I'm going to have to start hauling it from a station about 10 miles away, or go with additives. I have used Stabil in the past for over-winter storage, never had any problems with that either, but would prefer to just use eth-free since I've had excellent results with it.

To each his own I guess. It depends a lot on where in the country you live, availability of eth-free, etc. Find what works for you and stick with it is my motto. One solution rarely fits all situations. My method comes from 61 years of using and working on small engines, back when fuel was either "regular" or "ethyl" and octane rating was not yet a thing. My first experience with a small engine was at age 11 when my dad helped me overhaul a Clinton single cylinder engine off a garden tiller. My second one was at age 12 when I overhauled a (big to me at that time) Wisconsin single cylinder air-cooled engine on a Bolens 800 tractor. That was a huge project for a 12-year-old, but I successfully completed it. Back then we had to order parts by mail and sometimes wait weeks for them to arrive. Good ole days,huh?
 
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