Slick 60's

How long should the bottom end of an I6 last? Either new or after a rebuild?

Probably depends on the i6
The 240 / 300 have longer life than the 223 on Fords in my opinion

My uncle had a slant 6 dodge that had well over 300k on it

I've heard of 300 Fords going well over 300k miles

I have an 87 F150 with a 300. It has 205k on it. No signs of a bad bottom end. Even after my injectors went haywire and I drove with 2 quarts of gas in the crankcase for 35 miles. Burns a tad bit of oil (rings are on the way out)

My 66 F-250 ran like a top for what I believe was at least 180k plus miles. Would’ve ran a lot longer if the oil pump didn’t go out. Made it 25 miles on no oil pressure before throwing a rod (my gauges did’t work and I was going 65 with 4.56 gears. I couldn’t hear the engine knocking lol) Dropped a block in from an 86 w/120k and kept on trucking.

My 63 w/ 223 made it 125k before a rebuild. Looking over the papers the bottom end was fine. Needed to be bored .030 over though.

I’ve heard a lot of stories (in person and second hand) of I6’s going 200-300k plus without anything aside from regular maintenance.

Seemed to me the cylinders will give you trouble before anything else...

Not to mention industrial diesel i6 engines
We have a tractor with close to 11,000 hours ...
That would be over 1/2 a million miles at 50 mph
Never been touched .....

Maintenance & type of driving are more of indicator of life

no matter what anybody says, bottom ends will last only on some main reasons below ..
how you drive ???
how often you change oil ???
what oil you use ???
what oil filter you use ??? < FORD ONLY > no exceptions
how often air filter is changed ???
PCV Extra being changed ???
where you live in the country ???
type of gas using ???

bottom line engines will last only the way you take care of it,, doing it yourself then you know it's done right,, we personally take all trucks into Ford so if a screw up is a problem there is all the records in any Ford dealership across the country,, Rollback goes to Petro's so it's on record anyplace in the country,, DO NOT GO TO ANY OF THESE QUICK OIL CHANGE Place,, Had a friend go to one of those places, on a 7.3 powers stroke few days later called us, would not start when hot,, told him change oil to shell rotella 15w40 and get rid of that piece of junk WIX Filter, now truck runs fine again, and locally the county took their ambulance to local garage to do oil change,, few days later almost brand new diesel motor blown up DUE to WRONG OIL FILTER < WIX > and WRONG OIL and when Ford found this out NO WARRANTY, this was a engine with less than 30,000 miles AND 18,000 DOLLARS LATER

Fedex ran vans with 300 six. Most were sold as running, driving units when they reached 500,000 miles.