I've got a 2010 Honda Odyssey with 125,000 miles. Full-synthetic oil changes every 5,000 miles. Do I need valve adjustment? It runs fine and idles smoothly. Is it bad if I don't do it?
Yes it is bad if you don’t do it. You’d want to have it checked at least. If they are not more than 4,000 of an inch off, you can leave them alone and drive it. But on Hondas, they have a tendency of building carbon up and then having all kinds of problems later. The valves get damaged soon. So you do want to make sure that they are inspected at 125,000 miles. At least have them checked, and if they aren’t off too much, you can live with it. But if they are off, get them adjusted.