It's well known that some companies make more reliable engines than others, and there are many explanations of this from a corporate culture perspective. What I'm interested in is the set of physical differences in the engines themselves that create this variability.

Why, for instance, are Honda engines generally more long lived, reliable, and tolerant of poor maintenance than Fiat/Chrysler engines? Is it due to more precise tolerances, better materials, routing of oil and coolant passages, general geometry of the engine parts, etc?

Why do some engines build up more sludge than others or have different levels of piston ring wear? Why are some engines more resistant to developing rod knock than others?

Any insight into any reliability determining characteristics would be appreciated.

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    Welcome to the site! Your question is interesting, however it is too broad and therefore likely to be closed. There are many things that make an engine reliable, enough to write a book. – GdD Mar 6 '19 at 8:39

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