I thought I was very clear in my comment. But since I wasn't, let me state again,,,,
there will come a day when the government will ban the use of all pre-emission diesel engines.
When that day comes it will matter not how many hours a year we run our units, or what their life expectancy is, or how well we maintain our units.
In the Construction Industry it's already starting. It will eventually reach down to you and I, if we live long enough. Which was where my first comment came from "Depends on how near death you are". No Red Herring intended.