You mentioned Diesel, so I was curious.
My Step-father is the service manager at a local International Trucks dealer.
He is always telling me the importance of taking care of routine maintenence on Diesel engines to get the most lifetime miles out of them.
Yes some truckers are very good at keeping their rig healthy others not so much. I have to laugh sometimes at the cheapskates that will get their oil changed at a cheap place with crappy oil and filters, then have problems that will cost them thousands.
A certain cheap plastic WIX fuel filter has cost many 1k to 3k in injector replacements.
Cheap shops don't even grease the Chassis causing failed steering parts, u-joints and kingpin seizures if you let it go long enough.