reliable/long term car engine

Toyota 1HZ – Legendary 4.2L inline-6 diesel. Gear-driven + a tiny belt you could change blindfolded. No turbo, no drama. Just runs.

Nissan TD42 – Another 4.2L monster. Gear-driven timing, available NA or turbo. Simple and stupid tough.

Mercedes OM615 / OM616 / OM617 – Fully cast-iron classics. 4 to 6 cylinders. Giant double-row timing chains. Proven in every desert on Earth.

Jeep ERH (4.0) – American iron at its best. Inline-6 gas engine with crazy low-end torque. Built to idle through the end times.

Cummins ISF2.8 – Compact 4-cylinder turbo diesel with common rail injection. Cast iron everything. Built for hard work.

Opel C24NE – 2.4L gas 4-cylinder. Iron block, iron head. Ultra-basic design = huge lifespan.

Mercedes OM314 – Old-school 3.8L industrial diesel. 4-cylinder, gear-driven cam, no turbo. Tiny footprint, giant heart.

This list sticks to fully cast-iron engines only.
there are plenty of other legendary “million-mile” motors out there with aluminum heads.(but those are not really meant to last a million-mile)