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This section is for for those who want to take care of their own power equipment. I would suggest reviewing the section on SAFETY before continuing. Power Equipment causes far to many injuries and even deaths every year and a few precautions prior to using or repairing your equipment shouldn't be overlooked.
Generally this is what is known as gas. Those of us who grew up with "Muscle Cars" once used real gas. What we buy at the pump today in no way resembles it, except it still runs engines, or tries to. Todays motor fuel is loaded with ingredients only a chemist can pronounce, least wise understand it's function. The whole purpose is to enhance cleaner exhaust emissions, not to enhance engine performance. The "Shelf" life of the stuff is non existent, unless you consider 30 days much of a life. It may run engines when it's older but starting a cold engine will begin to become progressively difficult. Old fuel (over 30 days young) will begin coating the insides of the carb with a shellac type goo, valve stems can become stuck to the valve guides, poor combustion will cause excessive deposits in the combustion chamber and exhaust ports will clog up. Not a pretty sight. Depending on the original quality of the fuel, after two or three months it may not run anything.
Over half the problems we see in the repair shop are fuel related, and a note for those with equipment still under warranty. Fuel related failures ARE NOT WARRANTABLE. What YOU put in the equipment (fuel, oil) is YOUR RESPONSIBILITY not the manufacturer or the business you bought it from.
Avoiding old gas is simple. Don't buy more than you will use in thirty days. If the fuel in your re-fill can is approaching that time, poor it in your car where it can be used up before doing damage. If you know the equipment is going to set for an extended period, such as during the winter, put a fuel stablizer in a full fuel tank and run the engine for a few minutes to allow the stablizer to reach all parts of the fuel system. After the extended storage, the fuel should be drained and disposed in a proper manner and then refill the tank with fresh fuel. The old gas would have been difficult to start as before, but having had the stablizer in it will prevent the coating and shellacing from happening.

Using quality fuel is more important today than ever. Brand quality will vary from one area to another but normally, choosing a major brand from a busy station will provide you with the freshest, best quaility fuel. Most 4 cycle engines recommend 87 or 89 octane and 2 cycles will advise 89 to 92 octane. Remember, the manufacturers recommendation is the minimum. I advise people to use 92 octane for all outdoor power equipment. Quality control at the refinery is usually tighter on the premium fuel providing for fewer combustion deposits and more reliable performance. Using a major brand, high octane fuel from a busy station will give you better all around performance with less chance of problems.

Two Cycle Oil;

For many years folks have got away with using 4 cycle oil to mix with fuel for their 2 cycle engines. Indeed, that was what many manufacturers recommended. Not anymore. The same was true regarding the use of 2 cycle boat oil in 2 cycle outdoor power equipment. Unless you want to use your power equipment as an anchor for your boat, don't do it. 2 cycle outdoor power equipment today is a different animal. Twenty years ago a high revving 2 cycle would have turned 9,000 RPM, most much less. Today some are turning 16,000 RPM with the average around 10,000 to 14,000 RPM. Boat oil is made for relatively slow revving, cool running water cooled engines. Two cycle oudoor power equipment engines are air cooled and run much hotter. Boat 2 cycle or 4 cycle oil will cook a chain saw or line trimmer in a hurry. Todays 2 cycle air cooled power equipment requires oil made for them. Use one of the oils made for one of the "quality" 2 cycle power equipment engine manufacturers. Sure, it'll cost more but, pay me now or.........!

Mixing fuel/oil ratios for 2 cycles;
This is real important also. Most 2 cycle engines today are advised to have the fuel/oil ratio mixed at either 40 to 1 or more likely 50 to 1. In other words, 50 parts of fuel to 1 part oil. One gallon of fuel is 128 fluid ozs. Divide that by 50 and you come up with 2.56 fluid ozs of oil needed to mix with that 1 gallon of fuel. Just 2.5 ozs of oil, that's not much but it's critical to get it as accurate as possible. Never try to mix fuel/oil ratio's in the equipments fuel tank. You're not likely to get it right.
Todays equipment has little if any outward ajustability to compensate for fuel or air flow variables. This is so the engines can meet the new emission laws and not need to be recertified every year. If the carbs had the same easily adjustable and tamperable jet screws of the past the feds wouldn't allow the engines to be sold.
Oil added to fuel changes the fuels viscosity. This is the pour or flow rate. The change is minor but never the less it changes. The pre-set carb jets are designed to allow a precise amount of fuel/oil mix to pass into the engine. Not mixing the fuel/oil ratio correctly alters that fuel flow due to the viscosity change. Either way, serious engine damage can occur if the mix is too far off. It also alters the emission outputs. Thus, failure to mix the proper fuel/oil ratio, technically and legally, becomes a violation of federal emission laws. It's unlikey, at least in the near future, that you will be caught or fined but it's possible. Besides, if engine damage occurs due to improper lubrication, it won't be covered by warranty. Need a boat anchor?

This is fairly easy. If you still have your owners manual, I'm sure you do, uh ohh, check it for any variables. Generally 4 cycles are good to go with a quality automotive 30w oil. For cold climates when the outside temps drop below freezing during the time of use, change the oil to a 5w-30 or 10w-30. When it warms back up change back to straight 30w. A single viscosity oil is best whenever possible for power equipment due to being air cooled and the resulting higher operating temps. In a pinch, the multi-viscosity oils are ok when it's hot, but change it out as soon as possible before the oil "breaks down" under the hot running conditions. As with fuel, sticking with a major brand is the safest choice for quality. My favorite starts with a "V", but I'm not here to try to sell you something.

Before moving on, allow me to go off on a bit of a tangent. When you head off to your local shop to get a part for your "mower", say a tire, control cable or blade, the counter person will ask a couple of questions. You know, make, model and year. If you say, "it's a Briggs and Stratton mower and it's just like the one some guy just left here with", well, you're going to get laughed at, birdied, or at the least have an annoyed counter person. Friends, Briggs and Stratton is far and away the largest selling small engine made and is found in dozens of variations and sizes world wide. But they don't make the equipment they power, period. When buying parts for your equipment or the engine powering it, get all the numbers and names you can find, look hard, some equipment makers don't seem to be real proud of their name and don't make finding this important info easy. That's why many people think their mower is made by Briggs, they don't hide their name. You may have some difficulty finding the numbers needed for parts but not the name. Most engine manufacturers do display their name very well. It's a good idea when your equipment is new, to write down all this info where you won't lose it, like, an owners manual. oops. After a few years crud and debris may obscure this info making it harder to find. Do this for both the engine and equipment, even for Honda where often the equipment and engine are both made by Honda. Many times the Honda equipment numbers are all you need for them but sometimes having the engine numbers when getting engine parts may come into play when engine changes occur but equipment changes haven't. Honda engines are found on a lot of equipment they didn't make also.


Some equipment will have different schedules, if you have your owners manual, check for any variations.

Oil Changes;
New equipment should have it's first oil change inside the first 5 hours of running time. If you only run your equipment a half hour per week, change the oil after a month on a new unit. New engines will have a lot of initial break-in contaminants and needs to be replaced early. No special break-in oil is needed, or advised, use the regular good quality oil you plan to continue to use. After that, change the oil every 25 hours of running time or once a year. If your equipment is used in very dusty conditions change the oil more often. Engines with an oil filter usually need less frequent oil changes in terms of hours used, check your manual or ask your dealer. If you use your engine in sub-freezing conditions in the winter you need to replace the 30 weight oil (standard for normal conditions) with a 5W 30 or 10W 30. Remember to return to the straight 30 weight when it warms up.
Three things to remember before changing the oil.
1. Start the engine and let it warm up, 5 minutes should do it.
2. Remove the spark plug.
3. Do not turn a 4 cycle engine up-side down. When getting at the drain plug on a mower, tip the mower no more than 90 degrees and do so with the empty spark plug hole pointing up. You may want to place a piece of plastic (sandwich wrap) under the fuel cap to prevent dribble. Don't forget to remove it when done.

A couple of additional notes. If your engine has a dipstick to measure the oil, there are two ways of doing it, depending on the engine. On American made engines the dipstick is placed in the screwed in position to obtain the correct oil level. On Japanese engines the dipstick is just set down but not screwed in. This goes for Japanese made engines sold as American engines such as the Briggs twin cylinder VanGuards. Engines without a dipstick fill hole will have a fill hole with cap only, about an inch or so from the bottom of the block. This type will be filled to the top of the hole. Be careful to remove all dirt and crud build up surrounding the fill/dipstick hole prior to removing the cap. Dirt falling in to the engine will act like sandpaper on the engine and cause pre-mature wear and failure.

Spark Plugs;
Spark plugs are cheap. Replace them when you change the oil. If you have a two cycle where oil changes aren't needed, replace the plug when you clean or replace the air filter. Plug gap and type ARE important. Check your owners manual for correct type and gap. All new engines since 1995 have been required to meet emission regulations and tampering with emission controls is illegal. Spark plugs are part of the emission package. Every new engine regardless of the equipment it powers, comes with an owners manual which states the emission / maintenance requirements and the plug type and gap. It's not likely in the near future that the consumer will be cited and charged with emission tampering, but the law does exist.

Air Filters;
Stuff a pillow in your face and see how easy it is to breath. I see a lot of equipment that has excess combustion chamber carbon build up and prematurely fouled spark plugs because the user hasn't serviced the air filter. What they've done is stuck a pillow in front of the carb and expected the engine to perform flawlessly. Duh! Mowers, tillers and other lawn and garden equipment live right next to the ground and it's an extremley dirty environment. Check the air filters condition every couple tanks of gas until you get a good idea how long you can go between air filter servicing. If you're mowing a lush green lawn the filter will probably be good until it's time to change the oil. On the other hand, a roto-tiller may need it's air filter serviced in less than an hour.

Filters come in two basic types. Paper cartridge much like you may be familiar with in your car and oiled foam. Some paper cartridges have a foam pre-filter, these usually are not oiled because over oiling can cause oil transfer to the paper filter and destroy it. When a paper filter gets dirty it gets replaced. Foam filters, if not deteriorated, can be washed in hot soapy water, re-oiled with 30 wt. motor oil and re-installed.

The Lawn Mower Repair Man's pages

The Lawn Mower Repair Man
Blade Sharpening
Keeping an edge
Equipment Selection
Choosing the right equipment
Where to buy
No service or full service
Injury avoidance