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Petrol guidelines for powered equipment

Petrol plays an important role in everyday life, powering everything from your car to your outdoor power equipment. However, all petrol is not the same. Knowing a few facts about your petrol can keep the engines in your outdoor power equipment running strong.

What’s the Difference Between My Car’s Engine and Engines Used in Small Power Equipment?

Cars have comprehensive fuel and engine management systems controlled by electronics and numerous sensors. You may not feel or hear anything going on when your car is running, but there are many measurements and automatic adjustments being made to account for things like humidity, altitude, temperature and the quality of the petrol being used. 

On the other hand, lawn and garden power equipment tools are designed to be compact and lightweight. These tools don’t have the space available for the equipment found in cars and so are much more sensitive to issues like petrol quality. 

Petrol Guidelines –

> Petrol Storage Life
You may not realize it, but petrol begins to decompose and break down into other compounds in as little as one month when stored. This is not normally an issue for most cars since people drive their cars and refill their tanks on a regular basis. Outdoor power equipment is often used far less frequently, sometimes as little as a few times a year, and then can be stored away for weeks, months or years until it is needed again. Any additional petrol is normally stored in containers that may only be refilled once or twice a year. This means there is a greater chance of the petrol breaking down and forming gum and varnish-like compounds that can easily restrict or block the tiny fuel passageways used in small engines. Any petrol remaining in your storage can or left in your power equipment for more than 2-3 months can lead to expensive damage to your equipment’s fuel system and engine. This is why we recommend to always use fresh fuel or specially formulated fuel mixes like STIHL 2 stroke custom lube or the ECHO Power Blend 2 cycle oils in your equipment.

> What you need to know about Ethanol and Methanol, or Bio-Fuel blends
Ethanol petrol blends have different characteristics that need to be considered when fueling your powered equipment. Much of the petrol sold throughout New Zealand does not yet contain ethanol, but there are some brands selling bio-fuel, E85, ethanol or methanol blended fuels. Most small power equipment engines (such as lawnmowers, generators, chainsaws etc) are designed to use fuel that does not contain any bio-fuel blends. Ethanol is a stronger solvent than petrol and can soften, distort, swell and damage some rubber and plastic fuel system components that petrol alone would not harm. The solvent properties of ethanol can also dissolve varnish and gum deposits that have previously formed inside petrol storage cans, petrol tanks or the equipment’s fuel system. When these deposits become dislodged, they can mix with the petrol and plug small openings and filters within the fuel system and cause costly damage to your equipment. 

> Moisture and Water in the Fuel
Bio-fuels or ethanol are “hydroscopic” and easily attracts and mixes with water, so any moisture in the air can be absorbed by the ethanol fuel blend. This moisture can corrode metal components in the fuel system leading to expensive repairs.

If enough water is absorbed, the ethanol and water will settle out of the fuel blend. The resulting ethanol and water mixture is heavier than the fuel and settles to the bottom of the equipment’s tank or your storage can, leaving a layer of fuel floating on top. With the ethanol separated from the fuel, the layer of fuel now has a lower octane level than the original ethanol fuel blend. If you originally bought 91 octane fuel, the fuel layer in your storage container now has a lower octane than what the engine manufacturer intended to be used, resulting in unstable engine operation, power loss and possible major engine failures.

This separation of ethanol and fuel can also occur inside the fuel tank of your equipment. Since the fuel is often drawn from the bottom of the fuel tank, the engine is drawing in a mixture of ethanol and water with no petrol and, in the case of 2-cycle engines, also has no lubricating oil. This ethanol/water mix is thicker than petrol and cannot easily pass through the fuel system. This can result in hard starting, unsafe high idle speeds, stalling and can ultimately lead to engine damage or fuel system failure, resulting in costly repairs. 

> Our Recommendations
Use a minimum of 89 octane petrol and always use fresh fuel. Only buy enough petrol that you can easily use up within a maximum of two months.

  • For air-cooled, two-cycle engines, use a quality mix oil that meets the engine manufacturer’s recommendations. All STIHL oils are designed to readily mix with all petrol grades
  • Shake your petrol can well when first mixing the oil, and any subsequent use, to thoroughly disperse the oil in the fuel mixture to avoid lean mixtures and prevent “settling”.
  • Petrol containing ethanol has a tendency to “lean out” the carburetor mixture when compared to petrol without ethanol. We strongly recommend not to use BIO-fuel blends.
  • Properly store your equipment. If your equipment is not going to be used for a couple of months, the remaining petrol in the machine should be drained from the tank and disposed of properly. To ensure that any remaining fuel is removed from your equipment, it is recommended to run the engine completely out of fuel to ensure the ENTIRE fuel system is clear.
  • Equipment should be serviced regularly by Wright's Outdoor Equipment Centre. Items such as fuel filters, fuel lines, carburetor diaphragms and spark plugs should be checked and replaced if necessary, as part of a normal engine tune-up.
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