With care and adequate routine maintenance the engine should be good for 100,000 miles. Other things not so much - belts are the shortest lived followed by clutches, CV joints, U-joints, gear boxes electrical items and the rest.
However, over revving, long periods of idling, running too hard before the engine is warmed sufficiently, use of low quality oil, infrequent oil changes, use of low quality fuel, infrequent air filter service, operation in extremely dusty environments, plowing snow, pulling trailers and performance modifications will drastically reduce engine longevity.
I have rebuilt more engines with less than 10,000 miles than I have engines with 100,000 miles not because the engine is not capable of 100K, but because the engine with less than 10K was used for mudding, raced, modified for more power, used almost exclusively for plowing snow (low speed, short distance and backing up the same distance as moving forward - most odometers run backwards in reverse or simply do not record distance in reverse) or idled in excess of 10 minute periods. At idle oil pressure is low, oil temperature increases, heat builds in the cylinder head due to low coolant flow and the cam operates at extreme pressures. Hot oil loses surface tension and the sliding motion of the cam against a stationary rocker arm pad or lifter can shear the oil film more easily than a crankshaft journal rotating inside a round hole.
How many miles can be expected is dependent on use, maintenance and operator.
However, over revving, long periods of idling, running too hard before the engine is warmed sufficiently, use of low quality oil, infrequent oil changes, use of low quality fuel, infrequent air filter service, operation in extremely dusty environments, plowing snow, pulling trailers and performance modifications will drastically reduce engine longevity.
I have rebuilt more engines with less than 10,000 miles than I have engines with 100,000 miles not because the engine is not capable of 100K, but because the engine with less than 10K was used for mudding, raced, modified for more power, used almost exclusively for plowing snow (low speed, short distance and backing up the same distance as moving forward - most odometers run backwards in reverse or simply do not record distance in reverse) or idled in excess of 10 minute periods. At idle oil pressure is low, oil temperature increases, heat builds in the cylinder head due to low coolant flow and the cam operates at extreme pressures. Hot oil loses surface tension and the sliding motion of the cam against a stationary rocker arm pad or lifter can shear the oil film more easily than a crankshaft journal rotating inside a round hole.
How many miles can be expected is dependent on use, maintenance and operator.
