bbforks,
Long time ago the first owner 60-70's the first owner kept the new lift truck an average of 10 years then sold in the used market. Many of these lifts were fitted with a Continential engine which at best an 8000 hour engine w/lots of TLC. Today end users are opting for a FMV lease contract with the most popular being a 5 year. It is no secrete todays engines can go 12K+. iIwas with Mitsubishi and we sold lifts to ABF for use at their break bulk terminals. Their in house program was to rebuild the engines at 12K hours, when they started tearing the engines (4G53) down they found that the original cross hatch was still was very visible in the cylinder walls, they just put the head back on & kept running them. The GM engines (4 & 6 cylinder) are a 8000 hr engine, the Nissan is a 12K +engine as well as the Toyota engiens.
Think you missed the point or I didn't make it clear - the electronic on trucks today are primarily there to reduce tail pipe emissions not to enhance the life of the engine - although a more complete combustion of the fuel will add somewhat to extending engine life as well as regular maintenance.
In my personal, situation I do change engine oil every 3K & trans fluid once per year, diff. lube every two years - oil is always cheaper than metal. Certainly there are other factors tht play into life of an engine - cooling, bearing, structual integrity, materials, vibration, tighter tolerances & toleerance control, etc. But years ago a car with 80K miles was thought to be almost wore out - not today.