[Ken]

I am not likely the one whose advice you should listen to on matters such as you asked, but with regards to the engine my practice has been if the fuel consumption rate has not changed and it is not smoking (any more than usual) to leave it alone.

[Bryan]

Amen, Jon.

I will say, however, that you should do an oil analysis at every oil change on the 8V92. On more than one occasion I prolonged the life of mine by catching internal fuel/coolant leaks by this method.

[Archived]

Ditto what the others said. If you do start to experience decreased engine power or increased fuel consumption on an engine of that age I think you may find that the injectors are more likely the problem than valve adjustment, especially if the injectors are the originals. As you probably know, it’s getting harder and harder to find mechanics with 8v92 experience (or who have even seen one), even at authorized DD shops. Therefore, it’s not a bad idea to spend some leisurely time tracking down an experienced mechanic so you have one lined up if you ever need one in a hurry.

[Jerry]

I’ve never owned a bus with the 8V92, but I have in over the road trucks. We never touched the valves, until 2-300,000 miles. I doubt you would notice any difference, fuel mileage or power.

I would leave them alone.