I want to buy a 89 f150 6cyl 5spd with 244,000 miles. Not original owner and odometer only goes to 100,000. Many thing replaced. Runs nice to 55, no plate cannot get on interstate. Body very nice. Is this a good 70 mph truck for the interstate? Should the motor last to 275-300,000 if it was well taken care of mechanically? I will only drive 50 miles per week. Just want a fun comfortable, affordable truck till I die in 30 years!
Thanks

 

I had a 1986 F250 with the carbureted version and a C6 automatic. The 300 inch 6 is a tank; cast-iron, gear drive camshaft, etc. The 87 and later had port fuel injection which gave better fuel distribution. The engine should last. An aside, I took good care of mine and the contractor across the street made fun of me and my little book. When I bought my new 1999 and put the 86 at the curb, he couldn't run across the street with a fistful of Benjamins fast enough.

 

I had a 1979 F150 with the 300 six in it and had it for 16 years. What a great engine. The only thing I ever did to the truck was replace the clutch and a water pump. When I traded it off, it still ran great and didn't use any oil. I changed the oil back then every 3,000 miles.

 

If you really want to see how it runs at 70, I'd find a way to do so before buying it. Either take your chances without plates, or swap out yours temporarily. If it's smooth at 55 it probably will still be smooth at 70, but personally I'd want to know for sure.