Mower engines and fuel type


#1

I recently bought a riding mower, as most of you already know.
My question is, would I be wasting money putting high octane fuel in the 19hp B&S engine of my rider(Craftsman with tight turn and hydrostatic auto transmission) and B&S push mower(Craftsman self propelled) motor. My CX-7 takes(recommends) high octane and it’d just be easier for me to fill the gas can up with it before/after I’ve filled my car.
I doubt any damage would be done using high octane, but could I be wrong?


#2

Use what ever the manual recommends. If you want to used higher octane gas for convenience and the manual recommends 87 for example, nothing is gained, no harm is done.


#3

A few years ago due to carb troubles from the gas available, I started using the non-oxy gas only. The local Mobil sells it as their premium for boats, ATVs, etc. That’s all I use, plus I only use the Briggs fuel conditioner in it year round. Its a little pricey but have not had a problem since. Carbs now have very tiny holes in the jets that can easily get plugged from fuel deposits. What you should do is up to you but thats what I do.


#4

The 50:1 mix that I buy for my 2 stroke rototiller is 92 octane. It contains no ethanol, but costs $5 a liter. The good news is that it did clear up the hard starting problem I had with the tiller. The bad news is that my corn didn’t come up very well and I had to replant. I didn’t use this fuel last year and didn’t have the problem with the corn seeds not germinating. ( I wonder if the corn seeds got angry about not having the output used for making ethanol to blend with gasoline and refused to grow).
On my 4 stroke push mowers, one with a Briggs and Stratton and the other with a Tecumseh engine, I use the same fuel that I do in the car–it is probably 10% ethanol. One mower I purchased in 1988 and the other in 1992. Although the newer mower has been used much more and is burning oil due to a lot of use, I’ve experienced no problems related to the fuel I use in these mowers. Your mowers don’t need 92 octane, but it doesn’t hurt them.


#5

You don’t need 92 octane, but I would suggest adding some StaBil gas stabilizer.
If you can find some marine fuel, as Bing suggested, that’s a good idea too.

There are lots of websites describing phase separation problems with 10% ethanol-containing gasoline. You may want to google a few sites for a better understanding of it.


#6

The only thing I will add is that if the mowers were mine I would just drain them completely of fuel at the end of the mowing season and not even risk the fuel going stale.
How fast gasoline goes stale seems to vary widely. I had some a few years back (Ethanol) that became total gunk in about 4 months and resembled sour milk.

A match tossed into a sample would not even set it afire.


#7

I drain mine too. And I usually use additive too. Except last winter. And now I have a can of bad gas and a sputtering mower. I kicked it, but that didn’t help.


#8

Use higher octane. You might not hear it but lower octane might knock under load. A mower mowing high or wet grass is certainly used at full load. The manual calls for higher octane on my professional riding and walk behind mower too.
Maybe because it is rated to run all day and mow acres and acres at once?


#9

I try draining my stuff too but the thing is unless you actually pull the bowl off, or unless its a Tecumseh with the drain button on it, there will still be some gas left in the bowl. Also it seems like after the float has hung down dry for a season, it likes to stick when you put gas in again. I usually keep a carb kit on hand for the gasket when it leaks again at start up. Sometimes I’ve had the best luck just leaving the stabilized non-oxy gas in it for the next season. Maybe fogging the carb would do it if you have access to the choke which you don’t on a snow blower. Best to drain if you can I guess, just being prepared for a leaker at start up.


#10

The best, easiest and safest way to prep your fuel system for storage for the next season, is to drain your summer use, 10% ethanol content gasoline out and dump a can of some thing like Trufuel which already has the additives you need. Do not just drain or run your engine fuel system dry. Over time, that can dry out the gaskets and seals. Your fuel system is designed to have gas in it. Just make sure it is ethanol free gas ( if you have easy access to it) over the winter which is stabilized. I do this to my outboards, hand tools and mowing equipment and all start like they were run yesterday, some stored as long as two years !

Two stroke stabilized Trufuel acts as a rust preventative too when used in four strokes and eliminates the need to fog through the carb. Leave this fuel in metal tanks to help prevent rust as well. Do not run equipment dry and leave it for long periods. If it’s longer then two years, re drain, start up and run with a fresher storage fuel. If your system is leaking or sticking when you refill in spring , it probably has been stored dry for too long. If you are stringent about this procedure, carb problems will be thing of the past and only need repair due to normal wear.

Using higher octane gas when not recommended is a waste of money.


#11

I have a snowblower with a Tec engine that I’ve drained for 20+ years and never had a problem with gaskets or seals drying out. In fact, I always drain all my small engines of gas at the end of the season and have never had a problem as a result.


#12

My Ariens Snow-blower with the Tecumseh Snow-King engine has a warning Do NOT use high octane gas. Not sure what would happen if I did.

I have a snowblower with a Tec engine that I've drained for 20+ years and never had a problem with gaskets or seals drying out.

My Ariens snow-blower has a gas cut-off just below the tank. I just shut it off and run the engine till it runs out of gas.


#13

My recent carburetor troubles has led me to install fuel shut offs on all my 4 stroke engines, @Mike. I no longer kill the engines with the switch, I shut off the fuel and let them run out of gas. The results won’t be conclusive until next spring though.

As for octane, it may be more difficult to start a low compression engine on high octane fuel. Especially when cold.


#14

Both of my snow blower manuals state to run dry for storage.


#15

If OP’s push mower is a Briggs, then (unless it is very new) it’s probably a flathead. This means compression is 8:1 or so, and ANY octane gas should be sufficient.

E0 gas IS preferred, but (depending on where you live) it can be a nightmare to get. I blanche at the thought of $5/qt canned fuel, but I might use it at the end of the season, to put the equipment away “wet.”


#16

92 octane will do no harm but provide nothing in return either. Avoid anything higher, though! I ran a tank of 115 race gas through my Toro years ago to cut my super-small lawn (30 minutes max). After 20 minutes, the engine had no power and sounded like I’d burned an exhaust valve. The race gas had heated the exhaust valve so much it wouldn’t close. The valve clearance had been completely closed up, and then some! It ran fine once it had the time to fully cool off. No more race gas in the mower!


#17

The “storage” assumption is that you’ll take it out of storage next winter. If you’re going to store it for a very long time, then things can dry up.

That said, if you’re going to store your snow blower for more than the summer, you’ve moved somewhere with much nicer weather and don’t need it anymore. Sell it. :wink:


#18

Also…suppose you have some 2-stroke 32:1 mix, and want to run it in a 4-stroke mower, rather than have it go stale. It makes a decent “top oil”…just remember that 2-stroke oil generally isn’t burned in a low-compression small engine, so you’ve effectively leaned the mixture a bit.


#19

@jesmed‌
My response was for those who have had leaking problems. You can drain the tank but if you habitually run the carb dry, you are more prone to these kinds of problems. We aren’t making this up. Ask any small engine repair man. Just draining or “running dry” which never happens completely with ethanol laced gas with it’s residue still in place is not completely removing the effects of ethanol. Replacing it is.


#20

I’m not asking about storage, I’m asking about using high octane to run either mower.
I don’t have the push mower’s manual handy, but the rider’s manual says(the one thing I didn’t really look at) regular unleaded, and that a 10% ethanol mixture is ok. Anything higher will void my warranty.
As an aside, the manual also says to not mow wearing shorts or open toed footwear.

I had my push mower sitting for over a year without use after I ran the tank out. I put fresh gas in and it started up in less than 5 pulls It’s a self propelled Craftsman, and it doesn’t have anything I need to push before I pull the cord to start it up. I DID have a mower that I needed to push something on the side of the engine a few times before I could pull the cord; not sure what brand, or how old it was, though.