Hey im new to this site just wanted to say whats up an see if anyone else had gotten as many miles out of their 300ci inline 6. My truck is a 1980 ford f100 custom that my grandfather purchased new anpassed down to my father then to me. Obviously it has the big 300 an thats about it lol, 3spd manual, no power steering, no power brakes, crank windows an no ac but i love it an imma chevy guy. Over the years we have racked up 430,000 miles with no rebuild or any other type of major work can you beat that

 

That is pretty impressive! I rebuilt mine at about 230k but that was only because the freeze-out plugs started leaking and spraying coolant. I had to pull the motor to get at the back ones so I did gaskets, rings, and bearings while it was out. It was still running strong though.

 

Mine's only got about 76k, unless it has rolled over at some point already. Though I doubt that.

 

yeah i can thank the alabama weather for keepin the freeze plugs intact but i can also thank it for rust. I love these motors an trucks because theyre so simple any problem i have i can usually fix in about 30 mins. And holy crap do they have torque im runnin my exhaust through a cherry bomb glass pack at idle it sounds like a tractor but get on it an it turns into a small v8 lol. really turns heads

 

I love the sound of the 300 through a cherry bomb that is exactly what I did. I have it right after the cat pipe.

 

I swear by those 300 sixes, they run forever and you just can't hurt em. Never had one do me wrong.

 

I need to do a ring and valve job on mine.

Mine just past 600,000.

 

I need to get a 300 !!! my diesel has 240,000 and is runnin super strong all original

 

SIX HUNDRED thousand miles? Are you serious? That is just amazing!

I know these are old Fords, and the I-6 is one of the strongest motors ever produced, but please tell me, 81-F-150-Explorer, what are some of your best tips, secrets, and advice on keeping an engine running that long?

For example:
How often do you change your oil?
What oil do you use?
What other fluids do you use, and what is your maintenance schedule?
How often do you replace your spark plugs, and which brand?
What brand replacement parts do you use when you have to?
Have you done anything to your engine to keep it going this long, like do you use any sort of additives (Seafoam, Marvel Mystery oil, etc.)
Driving technique. Do you generally drive it easy or hard? What rpm do you shift at?
Do you do anything special or any particular settings to your carburetor? How often do you tune it?
What brand and grade of gas do you use?

Thanks for any and all of your advice. And congratulations!

 

you guys may clobber me for this, but....had a chevy 250 six...loved it...last i heard it had over 300,000. am putting in a 300ci from a donor truck. after hearing you guys...i am holding on to the old six and rebuilding at a later date. donor: 81 F150, miles unknown, recipient: 86 F250, miles unknown

 

lariat 85, the chevy had nothing but Mobile 1 synthetic.....i actually wish i could have found a 240 ci six. loved mine, wonder what gas mileage diff would be. to me, it had plenty of power

 

The highest mileage 300 six ford I personally have knowledge of has 317,000 miles on it. It belongs to a friend of mine. He bought it new in 1981. Basic maintenance has been done, fuel pumps, water pump, carb cleaning, alternator, belts, hoses.... You get the idea. But the engine has never been apart, valve covers included. It needs 50 weight oil or some STP to hold its oil pressure when hot. And it smokes on start up or going down hill. It is still being driven to work every day. Clarence has changed the oil every 5,000 miles and has never gotten over 60mph on the flat roads here in this part of Arkansas. Usually he is driving much slower than that. The truck has a lot in common with Clarance it doesn't due much more work than is necessary. I'm curious how many more mile either of them have left? but I may be surprised.

 

in the last two years, i have bought a 1981, 85, and 86. if mileage sez 95,000, hey you dont know if that is, maybe, 195k, or 295k, or...or....or

 

Yep, I'm serious.

I follow the maintenance schedule in the Owners brochure. But I'm a little more conservative.

I change my oil and filter every 3500 miles or so. I use Motorcraft Oil and filters. 10W-30 or 10W-40 as of late.

I have a "A", "B", and "C" maintenance schedule, and I post the mileage and schedule on the door pillar with a Dyno lable maker lable.

When a "A" schedule is due, aproximately every 3500 miles that is just an oil change and chassis lube. check the timing, adjust the carb if needed, Lube the tailgate and door hinges, and all moving parts etc... Check the air filter, water in the battery, and radiator, the hoses and belts. Replace when needed etc...

When a "B" schedule is due, aproximately every 7000 miles, I due the "A" schedule, plus check and clean the spark plugs, replace if nessecery. Replace the Fuel filter and Air filter. Check the Cap and Rotor and plug wires. etc...

When a "C" schedule is due, aproximately every 20,000 miles, or 2 year interval. I change the oil in the transmission, and rear end. Change the coolant, replace the radiator cap, check the gas caps, due a full tune up, spark plugs, cap, rotor, O2 sensor, PCV valve, check the EGR valve, check the spark plug wires, replace if nessecery. etc... I due the "C" schedule just before the required smog check here in California.

I swap them at 20,000 if they need it or not. However I clean and check them aproximately every 7000 miles or so, and replace them if needed then as well. I use Motorcraft, BSF-42-C plugs.

Motorcraft parts when I can. I will use Bosch, Trico, and Borg/Warner parts because they have supplied parts for motorcraft in the past and are usually OEM quality, if not infact OEM without the Motorcraft brand on it. My original O2 Sensor stated, Manufactured by Bosch for motorcraft as example. So I'm not opposed to buying a OEM Bosch o2 sensor.

I use marvel mystery oil on occation. It freed up a sticky valve for me 5 years ago, so I am a believer in it. It's also a good fuel additive. I use mostly stabul additive in my fuel in the winter however. The fuel sold nowdays does not have the antifreeze in it to keep the carbs from freezing up as it once did in the past. I even put rubbing alcohol in my fuel on occation. It will absorb any water that may be in the fuel system and make it combustible.

Mostly highway driving. 55mph at 1900 RPMs.


1st gear: 0-10 mph
2nd: 0-30
3rd: 25-45
4th: 35-max

downshifting:
4th to 3rd: 40
3rd to 2nd: 25-30
2nd to 1st: 0 mph (not possible)

Factory specs. California would not have it any other way.

The carb? Whenever it's needed. The smog check station can adjust it with the sniffer in the pipe.

Arco, Regular unleaded. 87 octane.

Thanks. My valve springs are sloppy, the valve seals are leaking oil now, and the lifters are showing signs of colaspling on me right now. Been doing this in the last six months or so. But since the head is Factory original, I think it's done me proud. The lower half shows no signs of any problems. However, when I take the head off to be reworked, I'm going to check the cylinder walls. If it looks good, then a ring and valve job, check the bearings most likely replace them. Then new lifters and it should work as good as new.

 

let us know how it looks, please. i wrestled with fixin my eng, or replacing. under different circumstances, i would have gone the rebuild route.