Maintaining Small Engines

AMSOIL Synthetic Lubricants Independent Dealer SLS Associates
Maintaining Small Engines

Probably one of the most neglected areas of maintenance in our homes is the care of small engines and the equipment they operate. We have lawn mowers and tractors, snow blowers, string trimmers, leaf blowers, tillers, chipper/shredders, chain saws, pressure washers, generators, hedge trimmers and I haven’t even started on the recreational equipment such as boats, motorcycles, quads and snowmobiles. We use them, put them away and expect them to be ready to go the next time we need them.  Considering the abuse many of these pieces of equipment receive, it is a testament to the quality and reliability of some of this equipment that it continues to operate when needed.  It would be interesting to know, of all the equipment that is discarded because it no longer works, what percentage was due to lack of proper preventive maintenance and what percentage had actually reached the end of its expected service life.  I would bet that the majority of equipment failure is due to poor preventive maintenance practices.

If you want to get the most life out of your equipment, use AMSOIL Synthetic Lubricants and related products.  (You didn’t really expect me to say something different did you?)  I have been using AMSOIL Products for over 20 years and while I haven’t used every product they make, I have never been disappointed with any of the products I have used.  The oils stay cleaner, longer and don’t break down, the grease stays in place and doesn’t wash out and the fuel stabilizer keeps the fuel fresh, even in winter storage.  As a starting point you should always check your owner’s manuals for guidelines on maintenance intervals.  The information that follows will give you a very rough idea of what you should be doing but keep in mind that the information is based on “Normal” use and operation.  Ask yourself the following:

  • Do you use your equipment in extreme temperature conditions? (below freezing or very hot weather)
  • Does it operate in sandy or dusty conditions?
  • Does it continually operate under a heavy load or wet conditions?
  • Does it operate uninterrupted for long periods of time?
  • Does it serve multiple purposes such as a lawn tractor that is also used for grading or plowing, towing or blowing snow?

If you answered “Yes” to any of the above questions, you may need to increase the frequency of the maintenance.  Again, your best guide to start with is the owner’s manual.

Let’s start with some basics:

Fuel – Degraded fuel presents a major maintenance issue in small engines and powersports equipment. It can form varnish, gum, and insoluble debris that clog carburetors, fuel injectors and fuel filters. Carbon build up can form on the tops of pistons causing pre-ignition, rough idling and poor throttle response. Fuel related problems are only expected to intensify in the coming years as the ethanol content in pump gas continues to increase.

AMSOIL Quick Shot Gasoline Additive

AMSOIL Quickshot® (AQS) is a premium fuel additive formulated to thoroughly clean and restore peak performance in small engines and powersports equipment fuel systems. It also stabilizes fuel between uses and during short term storage. Its revolutionary technology focuses on three major fuel related issues plaguing these applications: ethanol, water, and dirty pump gas.

For longer term storage you need a fuel stabilizer. Gasoline is not formulated for long term storage and can begin to degrade in as little as 30 days. Left untreated, gasoline not only causes the problems listed above, it adds to the sludge problem, causes floats to stick, poor engine performance, starting problems, increased maintenance expenses and decreased equipment life.

While the recommendation used to be to drain all of the fuel from equipment before storage, it can be difficult to do and it exposes the system to other problems including the formation of rust and corrosion on the bare metal in the tank and fuel system and the drying and cracking of gaskets and seals. Some fuels are pretreated with oxidation inhibitors that allow them to be stored for short periods without forming excessive deposits, while other fuels have no inhibitors at all.

AMSOIL Gasoline Stabilizer

AMSOIL Gasoline Stabilizer (AST) reduces the oxidation process that occurs when fuel is stored for extended periods, improving performance, extending equipment life and decreasing maintenance expenses.

For best results, depending on how long the fuel will sit before being used, use Quickshot or Gasoline Stabilizer in your fuel cans every time you fill them. This will help insure the fuel you put into your equipment provides the power and performance you expect.  Also, after using the equipment, top off the fuel tank.  By filling the tank, you reduce the air space in the tank which reduces the oxygen available to begin degrading the fuel.

Oil – Don’t Skimp On The Oil. Just because it’s a small engine doesn’t mean you can use a lower quality oil.  In fact, it should be just the opposite.  Small engines typically have very small oil sumps and don’t hold a lot of oil. Many hold less than a quart, have no filter and no pressurized system to make sure everything gets the oil it needs, relying instead on a “splash” oil system. Add to that the temperature extremes and environmental contaminants such as dust and other particulate matter and you really put your oil to the test.

Oil is the “Lifeblood Of Your Engine” so it pays to use the best one you can get.  Small air cooled engines usually run hot (compared to water cooled engines). Heat is the enemy of the oil and can cause it to break down loosing viscosity, film strength and its ability to seal and lubricate the engine.  For years small engine manufacturers recommended using a straight SAE 30 oil because the viscosity improvers used in multi-grade oils didn’t stand up to the heat and shearing forces in small engines. (They barely stood up to use in automotive engines which were a piece of cake compared to small air cooled engines.) There was also a school of thought that said you should use a non detergent oil in small engines, especially those without oil filters.  Not to get into a long discussion here but any modern small engine, oil filter or not, should be run on a detergent oil. If you find an SAE 30 non detergent oil it will probably be API SA or SB certified and use of that oil will, most likely, void any warranty you have.    

In small 4-stroke engines oil should be changed after the first five (5) hours to remove any break-in wear particles and then at 25 to 50 hour intervals, depending on the sump capacity and presence of an oil filter. (larger oil sump and filter = longer drain interval.) If you don’t hit the hour interval in a season, you should still change the oil at the end of the season, before putting the equipment away for storage. With use, oil develops contaminants and leaving it sitting in the equipment for months gives those contaminants time to cause problems. By changing the oil before storage you have fresh oil (no contaminants) and will be ready to go when it comes time to use the equipment again.

AMSOIL 2-Stroke and 4-Stroke Motor Oils

AMSOIL offers 12 different small engine oils (six 4-stroke and six 2-stroke oils) geared toward specific applications, all synthetic, all will help keep your engines cleaner, run cooler and last longer. 

AMSOIL Oil Filters

Oil Filters – If your small engine has an oil filter, use good ones.  Saving a few dollars on a cheaper oil filter is probably not the way to go.  (The AMSOIL Small Engine Lookup may help but you will need to know the Engine Manufacturer and the Model Number of the engine.) The full flow oil filter removes the larger wear particles along with any particles that stick together (agglomerate) and become large enough for the full flow filter to remove. Ideal oil filtration is achieved through the use of both a full flow and a by-pass oil filter but that topic is for another page.  For this discussion suffice it to say that a quality full flow oil filter will keep your oil cleaner and help reduce wear within the engine.  Engines equipped with oil filters also have more oil capacity.  Having more oil capacity never hurts since the additional volume means the oil doesn’t work as hard.  If the standard spin-on oil filter is small, using a larger one can also help by further increasing the oil capacity and increasing the filtering and cooling surfaces. When going to a larger filter make sure to keep the following in mind:

  • You must have room to install the larger filter and it cannot interfere in any way with the operation of the equipment, Make sure you check all moving parts that are or come into the area of the filter along with anything that may make contact with the larger filter due to flexing or other stresses during operation.
  • The larger filter should have the same or better filtering ability in relation to particle size. 
  • If the original filter has a by-pass valve make sure the larger filter also has one and that the pressure required to operate the valves are the same.
  • Make sure the filter threads and gasket are the same.
  • While usually not a problem with small engine filters, make sure the filter can withstand the equipments operating pressures.

Air Filters – Use quality air filters and clean and/or replace them regularly.  A large percentage of the contaminants that enter your engine will come in by way of the air filter.  They should be cleaned regularly (every 5 to 10 hours of operation because they are small) and changed when they can no longer be cleaned.  For pleated type filters, cleaning should be done with a vacuum and soft brush and/or with low air pressure (15 – 20 psi) blowing through the filter in an inside to outside direction. Using high air pressure can damage the fine openings in the filter making them larger, thus letting larger particles through which can cause more damage. Equipment with clean air filters are easier to start, run more efficiently and last longer.

Foam type air filters are usually cleaned with warm soapy water and repeatedly dunking and squeezing until the water coming out is clean. Once it is clean make sure to rinse it well and set it aside to dry, usually 24 hours or more. With this type of filter is is usually a good idea to have a spare to replace the one being cleaned. If it is oiled foam you will need to re-oil it once it’s dry. Use the proper oil per the filter manufacturer and be careful not to over-oil it. Put oil on the filter, start squeezing it to work the oil throughout the filter then blot it with paper or cloth towels to remove excess oil. You just want the oil to coat the interior open cell structure of the filter, not plug any of the openings which reduces air flow.

Fuel Filters – While many pieces of equipment go for years without replacing the fuel filter, they should really be replaced every year or two depending on how much use the equipment gets and how important it is that it runs when needed.  If the equipment comes with a fuel filter, it’s needed.  Manufacturers don’t put them on just for looks.  They are also usually inexpensive and should be relatively easy to change.  A partially plugged fuel filter may allow the engine to start and idle fine but lack power when the throttle is increased.  Depending on when this occurs you may think bad plug or plug wire, fuel, air cleaner, carburetor / injector etc, when the only problem is the fuel filter.  

Spark Plugs – Spark plugs last forever, or at least they seem to with the electronic ignition systems found in most small engines today.  They do however wear out so if you want to keep your equipment starting easily and running smoothly, replace the plugs every few years. Make sure the replacement plug is the same as the one that came in the engine and has the proper gap.

AMSOIL Multi-Purpose Grease

Grease – Grease is a lubricating oil in a semi solid form.  It is the primary lubricant used in rolling and sliding elements such as bearings and bushings where it is not practical to use oil in its liquid state for lubrication.  Grease not only acts as a lubricant to the moving components, it helps to seal out contaminants from entering the component.  It is important that the grease used is of the right consistency and is compatible with whatever grease is already in the component.  For most applications, #2 Lithium Complex grease with a GC-LB rating will work fine and, unless otherwise specified, is probably the grease installed by the factory. 

If the greased components are subject to moisture contamination, make sure it has good water washout characteristics. NLGI, the organization that sets grease standards says a #2 GC-LB grease can have a water washout rating of up to 15% and still pass the test.  A good water washout rating will be under 5%.  When you re-grease, if the grease you put in previously comes out as a water emulsion, you need to find a better grease.  

Equipment with grease fittings should be checked every 5 to 10 hours of operation and re-greased if necessary.  The harder the component is worked, the more frequently it should be checked.  Be careful however of over greasing.  If the component is sealed such as with a rubber boot that expands when grease is pumped in, apply only enough grease to make the boot expand, not enough to cause it to leak out of the boot. If there is no seal, slowly pump grease into the fitting until a small amount of grease is coming out of the bearing or bushing then wipe it clean.  Depending on the component being greased, if you can remove any load on the component or slowly move it through its operating range while it is being greased, you will aid the grease in getting into all the areas where it is needed.

Belts – Depending on the application, the equipment may incorporate belts when operating to transfer power, change direction or increase or decrease the speed of the driven component. While there is not much preventative maintenance that can be done with belts, it is a good idea to periodically check their alignment and examine the belt for any abnormal abrasion, wear or significant cracking. Most belts tend to stretch with use. If there is not a spring loaded tensioner to maintain proper belt tension, you may be required to manually adjust the tension. If the belt is loose and there is no manual adjustment or the adjustments are at their limit, the belt should be replaced.  

AMSOIL Engine Fogging Oil

AMSOIL Fogging Oil (FOG) – While oil tends to coat metal surfaces in 2 and 4stroke engines preventing rust and corrosion from occurring in the short term, over time the oil either drys out or settles off, especially the vertical and horizontal surfaces within an engine.  Fogging oil is specially formulated to remain in place over periods of extended storage and helps prevent rust and corrosion and dry starts when the equipment is taken out of storage. For equipment that is in “Seasonal” service, putting it away properly at the end of the season will pay benefits when you are ready to use it again.  Wash it, blow it out, or do whatever is needed to remove debris and other contaminants from all the external parts. Change the oil and oil filter, clean or replace the air filter, replace the fuel filter, change the spark plug if it is time, lubricate bearings, bushings and cables, fill the fuel tank with stabilized fuel and fog the engine. Store it in a dry location. Spending an hour at the end of the season will save you more than an hour at the beginning of the next season, and in the long run, increase the life of your tools and toys. 

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