Why do diesel engines seem to outlast gasoline engines? Shouldn’t they be built with the same stress safety factors built in and fail at around the same rate?

Question

Edit: Specifically referring to passenger vehicles and consumer trucks, not commercial vehicles that i assume would be built to go much longer anyway.

In: Technology

Answer 1

Part of it is just in the nature of gas and diesel.

Diesel – lubricates the engine components when burned/used

Gas – washes oil away from engine components when used

Diesel – generally has lower rpm so wears less on rotating components and cylinder walls

Gas – higher rpm so equivalently so wears faster on rotating components and cylinder walls

Diesel – engines will tend to self maintain and if you drive 1-3k more miles than suggested before maintenance, it really wont hurt the engine much

Gas – engines require outside maintenance at precise intervals to run properly otherwise it self destructs

Diesel – generally built with longevity in mind and a mindset of “overbuilding” engine components and lightness of components is secondary

Gas – generally built with a mindset in finding a compromise between weight and durability which means things wont be as durable but your car wont weigh more than your house.

Diesel – often have chains and components designed to last the life of the engine or for extraordinarily long periods of time

Gas – often have belts and compenents that arent designed to last as long as the engine block but are easily, quickly, and cheaply replaceable

Basically those. Ofc you can dive into intricacies of exactly how the fluids differ and exact methodologies and what not but if u maintain your engine properly and take care of your car, there isn’t any reason your gas engine shouldn’t outlive the car.

There are some gas engines that display similar ideas about longevity and durability during design and have become extraordinarily long lived monsters. Two such engines I am a fan of are the Toyota 2JZ-GTE inline 6 and the Toyota 1UZ-FE v8. Both engines if left stock and properly maintained laugh at 200k miles and will happily do more. The average 2JZ is good for 300k plus and the average 1UZ is good for 400k plus which puts both into diesel longevity territory. And that’s just with basic maintenance and replacing things that need to be when it’s necessary.