Lawn mower manufacturers give recommendations on how often to change the engine oil, but these are just recommendations and sometimes contradictory. Additionally, you want to consider a few extra factors when changing your mower’s oil. So, if you are wondering how often you need to change your engine oil, you have come to the right place.
Let’s take a look at when is the best time to change your lawn mower oil and how different factors can affect how often to change the oil in your lawn mower.
The General Rule About How Often to Change Lawn Mower Oil
Unfortunately, there isn’t an agreement between lawn mower manufacturers on how often the oil in a lawn mower engine should be changed. But they all fall between a range of time, and this is 50-100 hours.
A lot of lawn mowers these days use engines that third parties manufacture. For instance, Husqvarna uses Kohler and Kawasaki engines in the majority of their lawn mowers. They even use different engines in the same model mowers. This is where things can get confusing.
If you look through the mower owner’s manual and the engine manual, you can regularly find different numbers quoted for the same mower. So, in my experience, it’s always best to go for the lowest number as this is the safest option. Every 50 hours or once a year, whichever comes first, seems to be the best approach and is the timeframe I always stick to.
Factors that Can Affect How Often Oil Changes are Necessary
The time periods quoted by manufacturers are so broad because not everybody’s situation is the same. We all use our mowers in different ways and under varying factors, such as where we live, the grass we cut, and the oils we use. So let’s take a closer look at the factors that can affect how often to change lawn mower oil.
Ambient Temperature
If you happen to live in an area that gets particularly hot, then the lawn mower is going to have to work that much harder to keep the engine cool during operation. Ambient temperature can vary extensively from state to state, so people in hotter climates will discover that their oil degrades quicker than those who live in cooler areas.
How Hard The Mower Has to Work
The harder a lawn mower works, the quicker the engine oil degrades. For example, if your lawn mower is self-propelled, then the engine is used for both cutting and driving. A lawn mower cutting a lawn on a slope or hill will have to work much harder than a mower used on a flat yard. This means if you have a hilly yard, you are going to need to change the oil sooner.
Type of Grass
The type of grass you cut can have an effect on how hard your lawn mower has to work and how quickly the oil will degrade. Coarse grass types are much harder for a lawn mower to cut; therefore, the engine will get significantly hotter during use. Tough grasses are certainly going to burn out oil faster than fine, thin-bladed grass.
Blade Sharpness
A blunt blade is going to cause your lawn mower to work harder. Instead of the blade cutting the grass in a single rotation, it will take additional blade spins to cut the grass. The result is that the engine will be under increased stress during cutting. Increased stress equals hotter temperatures in the engine and faster degrading oil. So, to increase the lifespan of your oil, try sharpening your blades more often.
Belt Tension & Pulley Condition
If any part of the lawn mower increases stress on the mower’s engine, then the oil will degrade quicker. These could be items like an over-tensioned deck and drive belt, as well as pulleys that don’t spin freely. These kinds of underlying problems on your lawn mower will increase how often you should change lawn mower oil. Correctly setting the belt tension and greasing your pulleys will add some hours to the oil’s lifespan and protect the engine.
Quality of Oil
One big factor in how often you should change lawn mower oil is the quality of oil you are using. No one really likes to pick up an expensive bottle off the shelf, but you get what you pay for.
Cheap oils, unfortunately, don’t meet the standards provided by good quality oil. This means they don’t have the durability, performance, and protection levels a lawn mower engine needs. Cheap oils may save you a few bucks at the cash register, but you’ll be back at the store much quicker looking for more oil.
6 Signs that Tell You When to Change Lawn Mower Oil
So, you can see that everybody’s situation is going to be different when it comes to how often their lawn mower’s oil needs to be changed. Therefore, sticking to what it states in your lawn mower’s manual may not always be the best solution. As a result, you’ll avoid any related problems if you can identify when the oil needs to be changed by identifying bad oil symptoms. So, let’s take a look at what signs you should be looking out for as your engine oil starts to turn bad.
Visual Appearance
If you regularly pull out and test the dipstick, you’ll be able to see how the oil changes as it degrades. I find it best to wipe the dipstick on a white paper towel and get a real good look at how much it has discolored. Clean oil has that nice yellow color, so a brown/black oil on your dipstick is a clear indication it needs to be changed.
Engine Sound
Once the oil starts to go bad, it no longer lubricates and cools the engine as it should. As a result, you’re going to hear the engine knocking and making some strange, unnerving sounds while it’s running. This is the sound of the internal engine parts banging against each other as they overheat and expand.
Engine Overheating
Once the oil is no longer able to lubricate and cool the engine, it will not be able to release the heat generated as it works. This results in a significant drop in performance. If an overheating lawn mower is left to continue running, it will most likely result in complete engine failure to the point that it’s unrepairable.
Smoking Engine
Overheating engines can cause the engine to smoke. The smoke signifies that the engine has gotten so hot that the actual metal structure begins to smoke. So, if you see smoke rising off the engine, you’ll know there is an issue with the engine being able to cool itself, and it is more than likely because of degraded oil or lack of oil.
Higher Fuel Consumption
If you don’t notice any of the previous symptoms, you could notice a change in how much fuel your lawn mower is using. A lawn mower that’s using too much gas results from an engine having to work harder than usual. So if you notice that you are filling up more often, it may indicate that your mower is in need of an oil change.
Engine Vibration when Idling
If your lawn mower is vibrating really bad or has a new rattle when it’s idling, then it more than likely needs an oil change. Burned-out oil or low oil will cause the engine to rattle as the internal parts, such as the pistons and crankshaft, bang against the engine case. This is more noticeable during idling as the parts are moving slower. At higher engine speeds, the engine will be much louder than usual.
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