Cylinder Wall Wear vs Engine Operating Temperature Graph - 60-Hour Test Chart

This scanned manual page presents a graph titled "Cylinder-Wall Wear vs Operating Temperature, 60-Hour Test." The chart plots cylinder bore wear in inches (from 0.001 to 0.010 in.) on the vertical axis against engine operating temperature in degrees Fahrenheit (40°F to 200°F) on the horizontal axis. The curve shows that cylinder-wall wear is dramatically higher at low operating temperatures, approaching 0.010 in. near 40°F, and drops off steeply as temperature rises, flattening to roughly 0.001 in. or less near 160-200°F. The caption explains that a thermostat does more than provide quick warmup: bore wear increases dramatically at lower engine operating temperatures. The data is credited to Continental Motors. From this document a reader learns why maintaining proper engine operating temperature (via a functioning thermostat) is important for engine longevity, since running an engine cold for extended periods causes far greater cylinder-wall wear than running it at normal operating temperature. The document is generic engine reference material and contains no vehicle-specific year, make, model, or part number information, so it applies broadly rather than to any single vehicle such as the uploader's 1972 Ford Ranchero.