Now that I think about it, it was probably before the pandemic. 🤔
For the money you save by not doing the oil change you can probably afford a new mower every 10 years or so.
How often were you changing the oil in your mower? I own an electric lawnmower now, but before that I just changed the oil once at the beginning of each mowing season.
I only changed it once with the extra can I bought with the mower but never since. I’d imagine it easily costing somewhere around 20 to 30 euros a year so that’ll pretty much cover a new mower every 10 years.
Lawnmowers only take about 16oz of oil and you can buy 5qts(160oz) for $23 here in the states. So that $23 would last 10 years of oil changes if you replace it once per season like I did.
Not sure what that would cost you in Europe. So maybe that’s where the disconnect is.
If it’s a Honda, it’s fiiiiiine
Probably due an oil change about 2029
I thought two-stroke engines mix the oil and fuel together? Every time you refuel, you should also be topping up the oil. Am I wrong?
I knew some folks with a repair shop as a kid and got to use one of these.
I’m not sure you can even buy a two stroke lawnmower. Snowblower, maybe.
Yes, you need to have oil mixed with the gasoline in a two stroke, because the area under the piston (where the crankshaft is) creates the vacuum on the upstroke to draw in the next fuel charge. Lubrication of the crankshaft bearings, then, must come from oil that is in the gasoline, either by premixing it, or from an oil injection system.
A four stroke, on the other hand, uses the top of the cylinder, above the piston, to draw in the next fuel charge through an intake valve, and the area underneath the piston is bathed with oil. Over time, that oil (including its additives) breaks down and loses its lubricity, and must be changed for fresh oil.
I’ve got and used them.
Making sure I’m reading this right - are two and 4 strokes oriented differently? I always thought both were above the cylinder.
Orientation isn’t terribly relevant, although it is easier to design a two stroke engine in an “odd” orientation, because it does not have to be concerned about engine oil draining back into a sump.
In the simplest kind of two stroke, the compression and intake happen at the same time. Piston goes up (toward the cylinder head), compressing the fuel in the combustion chamber, while at the same time, fuel is drawn in beneath the piston, around the crankshaft. At top dead center (ish), spark occurs. Combustion powers the piston down (power), while at the same time forcing the fuel charge from beneath the piston into the combustion chamber via a transfer port, which also directs the exhaust to exit the exhaust port.
These two strokes - one up, one down - are one complete “cycle” of the engine’s operation.
In a four stroke, starting with the intake stroke, the piston moves down and the intake valve opens via a camshaft. Intake fuel charge enters the cylinder between the piston and cylinder head. The next stroke is compression. Both intake and exhaust valves are closed as the piston goes up. When the piston is all the way up (ish) to the cylinder head, spark occurs, causing combustion. The intake and exhaust valves remain closed, and the piston moves down. That was the power stroke. The next time the piston moves up, the exhaust valve is open, and exhaust is ejected through it. Intake, compression, power, exhaust; or colloquially “suck, squeeze, bang, blow.” Those four strokes complete one “cycle” of the engine’s operation.
Each engine has a crankshaft. This is the rotating shaft on which the piston is attached with a connecting rod. On the crank end of that rod there are bearings. (Two strokes will use roller bearings while four strokes will (usually) use flat bearings.) The connecting rod attaches to the piston with a wrist pin bearing. These bearings require lubrication. Without a thin layer of oil between the metal surfaces moving against one another, friction will quickly create heat and catastrophic bearing failure. (A four stroke also needs lubrication of the valve train, contained in the cylinder head; two strokes have no valves, and so no top end lubrication is required.)
A four stroke engine accomplishes this lubrication with thick engine oil. Most commonly, this oil collects in a “wet sump” oil pan at the bottom of the engine, is picked up by an oil pump, and circulated through the engine, being directed at the parts which require it, finally draining back into the sump. (There are also “dry sump” systems, where the oil resides in an elevated oil tank.)
A two stroke engine - since the crankshaft portion is also the engine’s fuel intake - does not have an independent oiling system. Such a system would interfere with the fuel intake, so the lubrication for the crankshaft bearings has to be included in the fuel. As described previously, this can be either with an oil injection system, where oil in a separate reservoir is delivered directly into the crankcase, or by premixing thin two stroke oil into the gasoline. In either case, the two stroke oil provides lubrication to the crankshaft, and then is burned in combustion. This is why two stroke engines have tha blue exhaust plume; that’s the two stroke oil burning.
Two strokes also have incredibly good power to weight ratios, mainly because they have twice as many power strokes per engine rotation. They are also incredibly simple, what with not having camshaft and valve train. Why don’t we use two strokes all the time then?
Well, mainly because they burn oil by design. But they are also noisy, and their design makes them severly RPM limited (they’ll lose power as they’re unable to intake enough air/fuel to keep running). Where two stroke engines shine is in very small applications (weed trimmers and model airplanes) or very large applications (industrial and maritime), though the latter makes use of fuel injection as opposed to carburetion, and does use a wet/dry sump engine lubrication system.
Mine burns a little oil, so I just keep adding it. That way it gets a perpetual oil change. guytappinghead.jpg
I think most mowers are two stroke engines, which generally are designed to burn oil.
Nah, most push and riding mowers are definitely 4 stroke. You’re absolutely correct that 2 strokes need to burn oil and create some visible smoke (to be properly lubricated). Only small, powered equipment (such as trimmers, blowers, and chainsaws) are still commonly made with 2 strokes. My smoking push mower was made in the mid 1980’s and is miraculously still running. It apparently has worn seals that are allowing crankcase oil into the combustion chamber.
Cool, did not know that! I have to admit I made assumptions there, figuring 2 stroke engines are probably more appropriate for smaller equipment. But I guess since you don’t have to carry a mower, a heavier engine is not a big deal, makes sense.
Good luck with your mower, no need for something else as long as it’s still working! After all, with a lot of things they really don’t make em like they used to, that old mower could serve you for a very long time.
Most mowers are four stroke like automobile engines, this includes pushmowers. Modern ones even have oil filters. Generally, riding mowers have two cylinder v-twin engines and pushmowers are single cylinder.
Two stroke engines are generally found on smaller things like chainsaws and weed eaters.
You mix special oil into the gas for two strokes. They do produce more smoke, especially when first started.
I’ve owned a car like that. Drove that thing for years until the driver’s side door fell off and I parked it.
Drain the fluids completely for Winter
Genuine question as I haven’t actually thought about this, how does that work when you don’t have a winter? Where I live it doesn’t get below 40° ever, or above 85°. Those are literally the overnight low in Feb, and midday high in Aug/Sep. Do I still need to drain, or just treat it like changing the oil in my car? I.E.: Every 6 months or 3500 miles, whichever comes first.
Like u/possiblylinux127 said, any time you’re not going to use it for more than a month or two, it’s best to drain the fluids. Oil is less important than gas, and you can leave gas in it as well if you add a stabilizer to it.
Personally, I wouldn’t use gas stabilizer for more than one season, but I know many who use it every year with no problem. Just make sure you run the motor with the stabilizer for a few minutes before you store it so the gas in the carburetor doesn’t gum up.
As for oil, I tend to only change it when it looks darker than a piece of burnt toast I’d still be willing to eat. I know that’s vague, but it’s how I do it.
Ideally, you should be using nonoxygenated gas for your mower, in which case stabilizer is unnecessary. The ethanol is what gums up carbs.
