Used wrong transmission fluid

[hmills]

ok, I'm going to admit it. I put Dexron III in my 71 F100 (original C4) and realized my error after adding 3 quarts and turning the engine on to warm up. I suppose I could drain it and add type F but i guess it has already mixed. any recommendations?

[390Nut]

Flush and re-fill with new fluid is the only thing I can think of. I don't know what type of damage could be done, personally, hopefully someone else here will know more. Interesting subject, as I had a buddy do the same thing once. He just drained it out, added some fresh type F, ran it up to operating temp and then spent a few minutes driving around the block a few times. Then drained and refilled again. Don't recall him ever having any major problems, but it was quite some time ago.

[68F250]

I would drain both the transmission and torque converter. One quart of Dexron is enough to ruin the properties of eight quarts of type F. Dexron is too slippery and will ruin the bands and clutches unless your C4 was rebuilt with Dexron compatible parts.

[spartman]

Okay what if a person put type F into a tranny that wanted Mercon then?

[68F250]

That's not bad but it will shift harder. Trick-shift as such fluids are type F.

[390Nut]

I would drain both the transmission and torque converter. One quart of Dexron is enough to ruin the properties of eight quarts of type F. Dexron is too slippery and will ruin the bands and clutches unless your C4 was rebuilt with Dexron compatible parts.

Ouch. That dont sound too good at all. Didn't realize it was so incompatable with the type F.

thanks for Tranny Fluid 101

[spartman]

Thanks Barry.

[68F250]

You're welcome guys but I don't think that's what hmills wanted to hear.

I have a Ford service training manual on transmissions and it goes into a lot of detail on the properties of type F vs Dexron with charts and graphs.

Incidently, from '78 - '81 Ford reengineered all their automatics to run on the GM type fluids. It was unofficially called the "anti-clunk" program because customers were complaining that the Ford transmissions were shifting too hard.

[qman]

Barry's got all of it right. Do a complete flush. It's real easy. First drain and clean the pan. Put the pan back and fill wilth fluid leaving the funnel in place. Then remove the return coolant line to the trans and clamp on a length (I have 8 ft.) of clear tubing. Run the tubing into a 5 gal bucket. Start the engine and the trans will pump the fluid out for you. Add a quart when about one has been pumped out. There should be about 4 qts in the pan so you shouldn't go dry on fluid and damage anything. My C6 holds (I think) 14 qts so I pumped through about 16-18 for good measure. I've done this with 4 vehicles and it works great.

[71-F-250SC-72-F-250C]

I did that once. It cost me $800.

[qman]

Why did it cost you $800?

[71-F-250SC-72-F-250C]

The transmission had to be rebuilt. Sorry I know you didnt want to hear that. I didnt realize that I had the wrong kind until I drove it about a day. So you might still be good.

[DuckRyder]

One other thing.

If you have not moved the shifter out of park DO NOT!

If you did, you will have to do the same when flushing.

If you drove it... That is bad...

[rjewkes]

why mine has ran on Mercon/dexron III for three years still shifts still doews everything and no band material in the pan yet? Maybe i got one that was built with dexron compatable stuff?

[DuckRyder]

Maybe i got one that was built with dexron compatable stuff?

Must have been or you would probably be walking...

See Barrys post for "why".