Two- and four-stroke recreational vehicles, hand-held power equipment, small engines, construction and farm equipment are commonly operated seasonally or infrequently, then stored for long periods of time. During these periods of inactivity, and as a result of fluctuations in ambient temperatures, water vapor can form condensate within the engine. When this condensate comes into direct contact with steel and iron components, it forms surface corrosion on cylinder liners, piston rings, anti-friction bearings and steel/iron contact surfaces on rotational seals. Long periods of storage can also dry out cylinders, often resulting in permanent damage when the equipment is taken out of storage and dry started.

    The severity of component distress resulting from extended storage varies, but it is usually not enough to result in immediate component failure. Often, equipment appears to function properly when put back into service, failing shortly thereafter as component distress increases with use. Because the failure doesn’t happen immediately, the equipment owner often does not suspect storage-related problems.

    The industry is beginning to recognize the relationship between storage-related corrosion and premature engine failures and performance problems. Most two- and fourstroke motor oils are formulated to have an affinity to engine component surfaces, acting as a barrier that keeps condensate from contacting engine components and forming corrosion. However, the effectiveness of motor oil in this area diminishes with time.