300 life expectancy.
New User
Joined: Apr 2003
Posts: 21
Likes: 0
From: dfw tx
300 life expectancy.
Originally posted by broncr
Put a big red mark (in your head at least) at about 3,000 Rpm on the tach, don't go past it and you'll double or triple the life of your Big SIX.
Put a big red mark (in your head at least) at about 3,000 Rpm on the tach, don't go past it and you'll double or triple the life of your Big SIX.
the valvetrain, otoh, is extremely rpm sensitive. big heavy valves/springs/pushrods don't change direction on a dime, so go easy on 'em.
New User
Joined: Sep 2002
Posts: 24
Likes: 0
From: waynesboro
300 life expectancy.
i have a 78 f150 and I just replaced my 300 which had 280,xxx miles on it. It just started to knock a little. I could've got away with re-doing the head but i figured I should just buy another block and rebuild it. So I bought a rough 75 f100 with a 300. My origional 300 would've probably run for another 100K miles. But now, I love my 75 300-6, it's so nice.
Elder User
Joined: Dec 2002
Posts: 695
Likes: 4
From: Metro Detroit
300 life expectancy.
Good advice uglytruckguy. I never beat on a cold engine. Thermal stability. Let it warm up, change oil every 3k, and keep it below 4k (or 3k for me) and it'll have a long life.
Posting Guru
Joined: Jun 2002
Posts: 1,288
Likes: 1
From: redding U.S.A.
300 life expectancy.
even when you beat on the engine, it'll still last forever.
My dad's old, old F-150 had about 350k on it before he sold it.
He thought the GVWR was the amount of crap you could put in the bed of the truck, with an oversized trailer and huge excavater on the back. He did things to that truck that should never be repeated.
He tells me he loaded it so much that the leaf springs were bending the wrong way. i don't know if thats possible.
I think as long as you don't really over rev the engine, it'll take all the low end beating you can throw at it. The 300 really is a great humble motor.
She'll just keep on ticking.
My dad's old, old F-150 had about 350k on it before he sold it.
He thought the GVWR was the amount of crap you could put in the bed of the truck, with an oversized trailer and huge excavater on the back. He did things to that truck that should never be repeated.
He tells me he loaded it so much that the leaf springs were bending the wrong way. i don't know if thats possible.
I think as long as you don't really over rev the engine, it'll take all the low end beating you can throw at it. The 300 really is a great humble motor.
She'll just keep on ticking.
Senior User
Joined: Mar 2003
Posts: 297
Likes: 0
From: KYLE
300 life expectancy.
I love my I6, enuf power to do what you need it to yet it doesnt get horrible gas mileage like a big block will (if you take care of the I6) the only problem i have ever had w/ mine is it blew the rear spark plug but that was my fault, i am running on 170K miles and it runs as good as the day i bought it. I have replaced the tranny, oil pan gasket, and a couple seals, but the engine is near perfect, i love using it to pull my drop top to car shows
Joined: Feb 2003
Posts: 559
Likes: 0
From: Toledo, Ohio
300 life expectancy.
I bought an '87 F150 off the original owner with only 30,000 original miles on it...got 33,000 on it now. Guess that old boy will be around for a while! 
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Freshman User
Joined: Dec 2002
Posts: 31
Likes: 0
300 life expectancy.
Every time somebody mentions "mileage" and "inline six" in the same sentence, there are always a bunch of replies. I hate to be left out, so here's mine. Best I've seen is 380K on my dads truck that he's still running. Trust me, I've tried to kill it, but the thing just wouldn't die. I've run it out of oil, gone 15k miles between oil changes, and run it hard when it was cold. The only thing I didn't do was was racing the motor-my dad did enough of that for both of us. No matter how fantastic a motor is, there are allways horror stories, but I've heard very few about the 300. By the way-Do*ge has the 225 slant six which has just as good of a reputation as the 300. The only short-coming of it is the lack of power. Che*y has that new 4.2L that looks like a fantastic design. The only problem I can see with them is that variable cam crap that is a neat theory, but runs off of oil pressure. They either have or will be bringing out a 3.5L inline 5 based on the same design, but thats a little small for fullsize. As much as folks here hate Che*y, they are the only one of the big three that is offering an I6 in anything. Its just too bad their new trucks are so UGLY.
Joined: Feb 2003
Posts: 559
Likes: 0
From: Toledo, Ohio
300 life expectancy.
Da Jeep I-6's!!! I live in the home of the Jeep (Toledo, Oh) and worked at the old N.Cove plant for 15 yrs in Security. The Jeep I-6 is an awesome powerplant for a 6 banger! Unfortunately the Germans seen fit to do away with the Cherokee, so the I-6 is now in the Wrangler only and I think still in cheaper models of the Grand Cherokee made in Detroit.
