I have read a lot of stuff on which tranny fluid to use on older trucks. Some people say F some say mercon after 1977. What is confusing me is the fact that the dipstick in my truck zays DEXRON II fluid only. So now I am not sure what to use when I drop the pan and change the filter out.

 

If the original stick calls for Dexron/Mercron, just use the newer III, it's compatible.

 

Yes, the original stick is authoritative so long as it hasn't been swapped out with another over the years.

A good reference would be the Owner's Manual; if you don't have one, then purchase one from eBay.

 

If you read the fine print on the new dexron bottles, it will usually say that it's compatible with all the previous dexron fluids. You won't find "dexron II" anymore unless you find some new old stock sitting on the shelf.

 

Thanks for the great info. I have 2 questions:
1) Can I verfiy the transmission type by the label on the transfer case?
2) If I am doing a pan drop and filter change is that the full 12Qts that I will need to replace?

The transfer case has 2 numbers:
1) a casting that says C-13683 (NP)
2) a new process gear label that reads:
208F and E3TA7 95RA 6 2 83 and at the bottom 261

The tag on the door jam says transmission code K.

Truck is 1984 f150 4wd 5.8l 351w.

Thanks for all the great help!!!

 

1. I don't think so - those numbers you list relate to the t/case itself.
2. The torque converter holds a big proportion of the oil, so for a full change it will also need to be drained.

If you remove the small access cover at the lower front of the trans, you can turn the converter until you get to the drain plug.

Here are some pics to id a C6

Older F Series .net • View topic - Automatic Transmission Info

There are slightly different bellhousings, but the transmissions are essentially the same.

 

Dexron = Mercon

Mercon = Dexron

Dexron is a Registered Trademark of General Motors Company. Ford bought the rights to use the Dexron name and fluid until Ford came out with their own Registered Trademark, Mercon. They are identical fluids.

 

Also FYI, *PRE* 1977 C6's that have not been rebuilt yet use Type F. Any C6 built after 1977 does not use Type F.

 

Flying in the face of sound knowledge, I have ran B&M Trick Shift (fancy name for Type F) with no issues. I noticed better shifts and less slippage when hot.

As others have said though, Dex/Merc is what the book calls for. I think (don't quote me on this) that Type F is kind of gritty in its composition, so it supposedly helps the clutches grip better. All I know is, my trans hasn't blown up or even hinted at wanting to, so...

 

Hey, Kirby, read this. I have no idea how true & accurate it is, but it might help:

MOTOR Magazine Article | MOTOR Information Systems

 

I was going to post similar to this but I did not know the year. I suppose some rebuild kits were out there for a while after 77 with the old style clutches requiring type F, but it is pretty safe to assume most everything on the road today takes mercon/dextron, or newer fluid.

 

Trick shift is not type F, it is nowhere near as harsh. It is Dex/Merc with a mild friction modifier in it, like adding a lube guard type product.

 

Very interesting read, thanks for sharing!

I didn't know that. I had read on here before that it was just rebranded type F so I believed it, since the bottle says it meets type F requirements, or some such.

 

Is there any difference in brands when looking for DEX/MER fluid?
There are so many brands out there and with having to buy 12qts I was interested to see whether expensive = better! I know motorcraft is around $6 qt.

 

There is a difference in brands. I used to work at one of the largest oil companies in the world and talked to the lube engineers frequently. They pointed out that I could see cases and drums of various brands of lube coming out of our blending facility - including Ford as we had the contract with Ford at the time. What they explained is that the big oil companies make a base lube that meets the minimum spec's, and then blend in the additives required by the various companies to meet their spec's. IOW, the base for a given lube, such as Type F, is essentially the same. But, Motorcraft Type F will have certain additives, O'Reilly's Type F will have different additives or volumes of the additives, etc.

Having said that, there are specialty lubes, such as Royal Purple and maybe Trick Shift, that may be made by small companies and might be quite different from others. But, if you aren't wanting/needing to go that way then stay with the standard stuff. And, within that if you needing to save some money the house brands of many of the auto parts stores, like O'Reilly's, have their own brand that meet the necessary spec's. That's what I've used in several of the trucks I've worked on and have had no problems.