How long can you dare without overhaul?

If it were me, ‘if it ain’t broke, don’t fix it’.

 

What kind of engine what kind of oil? I don’t have any answers for you but I’m curious to see what others will say. Subscribed

 

I'd leave it alone if it isn't using alot of oil and oil pressure is good .

 

Worst case scenario is to spin a rod bearing and have a rod go through the block. Rods and mains aren’t too expensive a job. Usually if oil pressures good. Bearings are good. Just watch the oil pressure. Chances are it will start mixing fluids first, or pushing coolant. Then it’s head home or to the Shop, ASAP!! A scheduled inframe will avoid that, and the worry till it happens. All depends on what you’re willing to risk. I ran mine right up till it almost quit. 3000 miles adding coolant, with a blown injector also. Thankfully, I made it home where I can get a fair price on an inframe. Last time I wasn’t so Lucky. Had to rent a Truck, pay tow bill, pay Dealership prices for an inframe, rent a car home, for 2 weeks. Cost was twice as much in 2008, as it was on my current Truck in 2020. This time I bought my Own parts, and had a Local Mechanic do the work. I only got what was necessary. I didn’t replace the rocker assembly, oil pump, or oil cooler. I may in the future. I think you can get a better built engine, by choosing the parts, and knowing the Mechanic. You have to look at it like any other maintenance. It’s inevitable. A basic inframe kit isn’t a whole lot of parts. Cylinder sleeves, rings, pistons , Bearings, oil pump check valve, and regulator. Seals and o rings. Add head(s) and injectors, maybe oil cooler, or a new oil pump, water pump, turbo, if wanted. Depending on their age. Dealer makes you change a lot of parts, to protect themselves from a warranty claim. Depending on length of warranty. I’ve heard of 1.5 mil, even 2.0 mil a few times. I personally would run it, rings are good, oil pressures good. But I take chances, many others don’t.

 

My n14 made it to almost 1.75miles, just keep working it

 

Different trains of thought TallJoe: I will start with believing oil has improved a lot over the years because of better additive packages. Don't thank that crankshafts and bearings have changed much. Oil filtration is also much better.
About 30 -40 years ago major company A changed rod and main bearings as preventative maintenance. That was done at about 350,000 miles and considered half life of a normal inframe. Later that grew to 1/3 life of an inframe as engines were running 900,000 to a million before inframe. They also ran the over head every 175,000 miles or so.
Major company B just ran them as long as life was good. Used a bit longer oil change intervals. I never saw any of their engines run 800,000 miles before in frame.
Now busting a million miles without having the oil pan off is no big deal.

From the equipment point of view: If a machine will get the job done in a day at 1800 RPM the same as it will at 2000 RPM then why run it at 2000 RPM? Yes the crank rides on an oil film and is never supposed to touch the bearings anyway. However it is only going to make so many revolutions it its lifetime. The difference in 200 RPM for a 10 hour day is 120,000 revolutions.
Will not stretch it out but bearings replacement maintains correct clearances and prolongs crankshaft life. From that same group of folks " Take care of the crank and the crank will take care of the bank" .
As for age that is not a consideration. We rebuilt a tractor engine a couple years ago. Bearings were dated 1974 and it was running all those years.

I kind of like the bearing change at estimated half life idea. You are so far into that I thank I would just run it.

 

I have 2 of the same engines, model and year, one 400hp turned up and the other 450hp. One has 940K the other has 1.1. Both have been solid other than some leaks that have been repaired.