Transmission Fluid

[Yardpilot]

351C C6. Three books, three different fluid recommendations. Type F, Dex III and Ford's own really spendy stuff. Which one of the first two is right? Will the wrong one do any harm?

[squirrel]

Type F will work, since that's what they used back then.

Dexron III should work also if you can't find F.

[Barry Donovan]

that should be safe to upgrade to the latest real standard. I still have a power steering with type A on the sticker. ignored it. got a miracle with a modern thing called "power steering fluid".

[Scott Liggett]

I seem to remember Fords get Type F. F for Fords.

[CDMBill]

Who built it, and with which clutches? There are plenty of inexpensive Type F rated fluids out there Chevron seems to work well, and the general feeling is that due to the additional friction modifiers in the Type F additive spec it will shift harder. If the build is stock spec Ford then Type F is the right choice. The second best Type F is B&M Trick Shift, the best IMHO is ATI Super F.

[anotheridiot]

I remember running F in a GM powerglide, something about less foam to Dex. Its hard to find alot of the older stuff. Last time I went looking for ATF 3 fluid for the Jeep the counter guy said you can go ahead and use the current ATF, I think it was 6 which is just upgraded fluid. I dont know if I believe that one. They ended up having a gallon jug of 3 that was the cost of two quarts of the current synthetic stuff.

[milner351]

Starting from a fresh rebuild, the best transmission guy I know runs generic dex/mercon in everything. But if you are only dropping the pan and putting in a fresh filter - you can't get all the old stuff out, it's best not to mix fluid types.

Is there a drain plug in the torque converter? That lets you get a lot more of the fluid out and would be less risk to mix.

[TC]

I remember running F in a GM powerglide, something about less foam to Dex. Its hard to find alot of the older stuff. Last time I went looking for ATF 3 fluid for the Jeep the counter guy said you can go ahead and use the current ATF, I think it was 6 which is just upgraded fluid. I dont know if I believe that one. They ended up having a gallon jug of 3 that was the cost of two quarts of the current synthetic stuff.

Using Type F is an old racer thing, F stands for Friction, because the old Ford Transmissions needed the added friction material in the trans fluid to work properly.......It was the thinking that using Type F in a GM PowerGlide(or the like) would make the clutches not slip as much, thus deliver more power through the transmission..... If there's any truth to it, I don't know, but it is what I've heard over the years from old time racers.....

[Beagle]

if it's never been changed and you've never put a filter in it and it has high miles, I'd leave it alone and top it off with type F.

I'm totally serious. I've wasted several automatics trying to do the right thing and changing the oil / filter at 100k or so.
Jeff, IndyShiftMan (who I still miss here) says I dumped all the friction material out with the change. I believe it.

[milner351]

^^^^ that is a true statement (I miss Jeff too) if it's high miles, top it off and don't mess with it.

[Yardpilot]

It was "rebuilt" before I got it by someone who did lots of fun things wrong. For example, a bushing in backward that heavily restricted flow. Other stuff, too, that's why it failed. I rebuilt it. Just me, a willingness to try and a bit of "book learnin'." Right out there in the driveway. I reused most parts if they looked good and specced out. I kept all tolerances as tight as possible. That means it doesn't rattle uncontrollably. Shifts like a witch. No idea what brand most parts may be. Running type F. Works. I was just concerned about the conflicting info. I haven't touched an automatic since the early 70's. That was a powerglide. Some folks object to calling those transmissions, but I kinda like them for what I did with them. I learned about using safety wire when a bell housing bolt backed out and contacted the flex plate. That'll make a believer outta you.