What are the most reliable engines ever made in terms of longevity?

[Stella_C]

I'm fascinated by engine design and want to know which engines deserve the title of most reliable engines ever made. Not just popular engines, but ones with engineering that stands the test of time. What specific engine families from which manufacturers have proven to be nearly indestructible with proper care?

[PaisleyBC]

For most reliable engines ever made, my short list would be: Toyota 22R-E (old pickups), Toyota 2UZ-FE (Land Cruiser/Tundra), Honda K-series (Civic/Accord), Mercedes OM617 diesel, GM 3800 V6, Cummins 5.9L diesel, and the Ford 300 inline-6. These engines have proven they can go 300k+ miles regularly with basic maintenance.

[Ethan_W]

The 4.0L inline-6 in Jeeps (the AMC design) deserves mention too. Not the most refined but incredibly durable. Same with the Ford 4.9L inline-6 from the old trucks. Inline-6 engines have natural balance and fewer moving parts than V6s, which contributes to longevity. The most reliable engines ever made tend to be simple designs without complexity for complexity's sake.

[Chloe.C]

What's interesting about the most reliable engines ever made is that many are no longer in production because they don't meet modern emissions or efficiency standards. The quest for lower emissions and higher fuel economy has forced engineers to make trade-offs that sometimes reduce longevity. Direct injection, turbocharging, start-stop systems all add complexity.

[Stella_C]

From a pure engineering standpoint, the most reliable engines ever made share design principles: low stress operation (low specific output), generous cooling capacity, robust bearing designs, conservative tolerances, and materials chosen for durability rather than weight savings. The Toyota 1GR-FE V6 is a modern example that follows these principles while meeting emissions standards.

[Larry.L]

The economic aspect is interesting too. The most reliable engines ever made often come from vehicles that hold their value well, creating a virtuous cycle. People maintain them better because they're worth more, which makes them last longer, which supports resale value. It's why Toyota trucks with these legendary engines command such high prices even with high mileage.