I have a 1984 F150 SC 2WD with a 5.8 HO and 3-speed C6 Automatic. I bought it myself new in 1984. It's has a little over 200k miles on it and is starting to look a little rough around the edges of course, but other than surviving a couple of teenagers learning to drive in the 90's, it hasn't been treated too harsh. It's been driven very little over the past 13 years, but I'm in a situation where I'm having to use it as my daily driver again, at least for a while. It will be driven about 95% in-town (45mph or slower) and 5% highway use. I've been doing some things on it this past year that have been kind of neglected for a long time and I have quite a bit more to do but it's in pretty decent mechanical shape. I had a complete rebuild done on the engine in 97' and it's only had maybe 5 thousand miles put on it since then so the engine is great. The brakes, suspension, and front end are in good shape and have been maintained. What I am wondering about is the transmissoin. It's working perfectly now and I have never had to do anything other than routine fluid and filter changes about every 20k miles through the years. I haven't changed the fluid and filter in about 8 years but it's been driven very little. I'm going to be changing the fluid and filter in the transmission this weekend but I was wondering because of the high mileage on this vehicle, how much longer can I expect the old C6 to survive ? Is there anything additional I can do to for it ? The truck has always been driven pretty carefully, and has seen very little trailering or hauling duty. I really need this truck to last me for a while and if anyone has any suggestions for what else to check or change out or what to look out for, that may not be obvious to me, I would be grateful for any and all suggestions but the main thing that is on my mind now is the transmission with all the miles on it.

Some of the things I have already done:

New 4 row radiator 40k miles ago - bi-yearly coolant changes
heavy-duty external transmission cooler installed when truck was new.
Engine rebuilt 5k miles ago
No oil, coolant, transmission, rear-end or axle leaks or drips
No unusual sounds, vibrations, wobbles or shakes
Small Power steering leak - add fluid about once a month.
New engine thermostat 192
Fairly new heater core
New brakes, wheel-cylinders, master cylinder and vac. booster
New tie rod ends
Good tires

It's hard to find gasoline here without ethanol in it and my 4 barrel carb doesn't care much for the stuff. Is there anything I can add to the gas to sweeten it up for my carb a little ?

Thanks in advance !

 

The C6 is well known to have a rather long life, when treated well. Sounds like you've treated yours much better than most do.
200K miles in ~25 years is not that bad. If it works good, it could last many more years/miles. If you are really worried about it, have it rebuilt at a reputable shop. Then, you could be pretty sure it could go another 200K and/or 25 years......

 

Thanks Rogue. I'm actually hoping I don't need to worry about rebuilding it. I guess I was wondering if the C6 was durable enough to go on with just routine maintenance, or if maybe 200k was pushing my luck. It shifts as good as the day I bought it and it's used just for plain ole transportation and some occasional very light hauling. And for what it has been used for, the C6 was probably way more transmission that it ever needed, so my concern is probably not warranted but I thought I'd get some other better qualified opinions on it. If it has a good chance of going another 50k or 100k without an overhaul that would be better than apple pie. It's still just as big of a gas-hog as I remember it being though.

I see you have 1980 F-150 with a C6 and 310k on it. That's very encouraging Rogue !

 

Even without rebuilding it i'm sure with the good maintenance you gave it, that C6 will go another 200k miles without a rebuild!

My motorhome has it's original C6 with 150k on it, and it's had the same 11,000 pound load on it since brand new!

 

Yeah, the truck has at least 300K on it. Could be 400K or more. I found reciepts proving over 200K when I bought it 13 years ago, and I've added another 120K since then (sig is old. Nissan has 240K, and RX7 hit 230K).
Of course, I've also had the C6 rebuilt a few years back. It was time. It *only* gave me 5 years advance warning before that little rubber O-ring let go...... My rebuilder was impressed. The clutch plates had almost no traces friction material left, yet it never slipped. As he put it, the only reason the transmission worked correctly in that condition, was due to a 4 letter word. F-O-R-D.


Of course, his 6.0 PSD has killed his belief in that 4 letter word......