Right from the start, I know this is a question that is too general to have specific answers but I wonder if based on the experience you have had with a Montero Sport (2000, 3.0), what would be a reasonable life expectancy for the engine BEFORE needing to do a complete engine rebuild? Mine, for example, has 207,000 miles and it is issuing white smoke from the tailpipe when starting from a stop, which means that it needs a valve seat job. I wonder, however, if it would also be close, in general, to also needing a complete engine rebuild? Thanks in advance for your guidance!

 

Do you think you've answered your own question?
Mitsubishi engines are generally long-lived, but usually you run into a lot more problems before the engine itself.
Good luck!

 

Have to agree regarding the problems. Just do the valve seat job, inspect the motor oil for shavings, check that oil is properly flowing, and other easy maintenance procedures. How much longer it will last before needing an overhaul depends on maintenance since 0 miles. Don't think about it until you get the obvious signs.