Twelve months is calculated by how much an operator uses the engine. For a commercial user a small engine operates approximately seven hours a day, five and a half days a week at 3600rpm. The number of hours for twelve months operation adds up to 2002 hours of use.
To compare, the average car with an engine running at 3600rpm has the ground speed of around 136kph. If 2002 hours is multiplied by 136kph, that is a total of 272 272km on the car.
It is also important to remember that small engines are not watercooled, some have no oil filters, and frequently operate in a dirty and dusty environment. Lets look at the oil—seven hours a day, five and a half days a week adds up to 38 and a half hours. Oil and an oil filter needs to be changed every 50 hours, that means it has to be done every seven days! If the engine has no oil filter then it has to be changed at 25 hours.
Protecting an engine from dirt is the main factor towards the engine’s total life span. If more dirt is allowed to enter the engine, the shorter the life span it will have. When the engine runs at 3600rpm, the piston will go up and down 216 000 times in one hour; over a week it will go up and down 8 316 000 times; after twelve months of use it will have gone up and down over 432 million times.
The air filtration system is the easiest place for dirt to enter the engine. On a car, the air filter is located on the top of the engine, enclosed by the radiator, guards and the bonnet of the vehicle. On a mower however, the air filter on the small engine is located about 400mm above the ground, with no protection, and like most small air cooled engines they are operating in a cloud of dust and dirt. Therefore it is important that on small air cooled engines air cleaner/ element maintenance is performed regularly.
The only difference between a short and long engine life, whether it is a car or your small engine, is the maintenance program you provide for your engine and equipment.
The better the maintenance program, the longer the engine life. You cannot afford not to maintain your engine and equipment.