This is an article that I have had in my possession for over 10 years it comes from Briggs & Stratton, I am not sure how long ago they published this but it is still good info. I thought it would help give another point of view, enjoy Let's take a look at what we mean by "only 6 months": As a commercial user, you realize that you Briggs&Stratton engine usually operates 6 to 7 hours a day. You are probably working from 5 to 5 1/2 days a week. The engine operates at 3600 rpm. Calculate the hours for 6 months operation and you realize 900 hours usage. Sometimes it is hard to comprehend just what we mean by 900 hours; let's take a look at your car for a comparison.: The average car with and engine running at 3600 rpm would have a ground speed of about 85 mph. If we multiply 900 hrs by 85 mph we come up with "76,500 miles". If we carry out this calculation for a year, realizing that as a commercial user you can operate each piece of equipment as much as 1800 hours yearly, this 1800 hours of usage calculates to the equivalent of "153,000 miles" on your car. We must remember, this small engine is not water cooled, has no oil filter and frequently operates in a dirt and dust laden environment. Let's examine a few additional facts: Protecting your engine from dirt is probably more relative to it's total life span than any other single factor. The more dirt that is allowed to enter the engine, the shorter it life span. With the engine running at 3600 rpms, the piston will go up and down 435,000 times in 1 hour! The easiest place for dirt to ingest into an engine is via the air filtration system. The air cleaner on an automobile is closer to the top of the engine, elevated about 3 feet or more above the road and completely enclosed by the radiator, fenders and hood of the vehicle. To further complicate matters, the air filter on the small engine is usually located about 1 foot or less above the ground, protected by nothing, and most small air cooled engines are found operating in a cloud of dust and dirt. Thus, it is evident that, on small air cooled engines air cleaner/element maintenance is of great importance and must be performed frequently in adverse conditions. remember, the only difference between short engine life and long engine life, whether with a truck, an automobile, or your Briggs&Stratton engine, is the preventive maintenance program applied to the engine and equipment. THE BETTER THE MAINTENANCE PROGRAM, THE LONGER THE LIFE. YOU CANNOT AFFORD NOT TO MAINTAIN YOUR ENGINE!