I have a 1980 ford f150. It runs well and I change the oil at the specified intervals. I only drive it about 3000-5000 miles a year. It is a house project/winter truck. It has a new battery, alternator, starter, solenoid, plugs, wires, distributor cap, and tires. It came with an edelbrock performer 4 bl carb and a edelbrock hi flow air cleaner and hi performance intake manifold. I am getting the brakes done soon. What do I really need to do to keep this thing running well and keep it up for the winter months? It starts well now and I want to keep it that way. It is a 3 speed and it shifts kind of hard. I am afraid to have the tranny flushed because i have heard once you do that problems arise. You either never do it, or do it all the time. Am I wrong here? It seems to be just fine now....but I want to be proactive. Also, can anyone tell me where all of the grease points are on this thing. The only ones I could find were on the front wheels and steering components.

 

That's it for greasing, unless you have greasable universal joints on your driveshaft.

Assuming a C6 trans, a few things could give harder shifts - one possibility is a shift kit having been fitted somewhere in it's history; also the modulator could be out of adjustment or faulty.
If you have a significant vacuum leak in the modulator line, or elsewhere, that will also affect the shifts.

 

You didn't mention it, you could do a cooling system flush and refill. One of those reverse-flush garden hose kits on the heater hose works well in my experience. Even the Ford factory shop manual recommended using a water-soluble chemical flush to clean rust/scale out of the cooling system. Refill with 50:50 antifreeze: deionized water.

Regarding the transmission fluid - I can't agree with the "never change it" theory. Heat, pressure, oxidation causes a lubricant to lose it lubricity. I would want to change it.

 

From what I hear, flushing "may" dislodge particles that otherwise is not causing problems right at that moment. I stressed with that issue on both my 85 and 92 when I first got them. Especially the 92, because it's high mileage E4OD (265k), and had never been serviced.

What I found is that a complete drain of fluid (TC, cooler, and trans), replace filter and refill with a quality fluid will revamp the lubricating requirements of your trans without causing too much stirring around of undesirables.

I did this to both my trucks with great results.

The 92's E4OD fluid was brown, with "stuff" floating around in the fluid. Smelt burnt also. The trans had a bad TC shudder, shifts were slow and felt weak. Did a complete fluid replacement and new filter. What an improvement!! Shudder went away, shifts are much more solid, and shifts when it's supposed to now.

The 85's C6 now feels like it has a shift kit installed!

My suggestion is, and take it for what it's worth, is to replace the fluids and filter. No fluid lasts forever, and neither will your trans if you don't service it from time to time.

BTW, don't let some transmission shop talk you into a power flush. They will break your transmission. I think that's where the negative urban legend of servicing high mileage transmissions comes from. It's not that they were serviced, but that they were serviced by idiots.

 

I flush my radiator fluid every 3-4 years (I use the orange stuff). When I was using the green anti-freeze, I flushed every 2 years. I also flush my brake fluid every 2 years, which is what you are supposed to do if you live in a high humidity area like me.

 

The C6 is a rather stout trans, if that's what you have. I would check the vacuum line as suggested above, and possibly even consider a modulator valve replacement.
As for the fluid flush, like said, the fluid gets old and loses the ability to properly lubricate the internals. A C6 "filter" is just a screen, to keep out the bigger chunks. The rest can continue to circulate thru the system, or settle to the bottom of the pan and inside the converter.
Flushing the old fluid out typically does no harm, but it also never hurts to change the screen. Ford made it easy to get ~90% of the old fluid out by dropping the pan and pulling the converter drain plug. Doing this yourself would be much cheaper than the typical cost for having a shop flush the trans.
Proper care will lead to a longer service life of the trans, and a C6 can go over 200K easily when cared for and treated well.