And that engine would last just as long with 5k intervals and at half the price. He could leave his kids a bigger inheritance instead of just leaving them a tired old truck
I get what you’re saying about wear at one oil change, but there’s another angle that matters more if the goal is a truck that still runs strong at 250k–300k miles.
When you drain the oil you never get it all out. There’s always some left in the pan, passages, cooler, and filter housing — usually 5–20% or so. That residual oil mixes with the new fill.
With a 5K interval, the oil you leave behind has already seen 5,000 miles of real engine time (heat, oxidation, additive depletion). You add fresh oil, but some of that new oil then becomes the residual for the next 5K change. Over 10 years, portions of the oil in the engine can end up with 8–12+ years of cumulative engine time on them, even though you’re technically changing it every 5,000 miles.
With a 2,500-mile interval you’re doing a bigger partial refresh more often, so the average age of the oil that stays in the engine stays lower over the long haul.
I’m not saying a 5K interval will kill an engine. I’m just saying that keeping the average age of the oil lower gives you the best shot at minimum cumulative stress and deposits over many years.
Different goals, different approach. If 5K works for you and you’re happy with it, that’s fine. I’m just optimizing for the longest possible engine life, not the lowest cost per mile.
