My 02 5.4 with the 4r70w is closing in on 80K miles, and I suspect it has never had the fluid changed. It isn't burnt, but I think it is about time for some fresh fluid. I tow a moderate load with the truck and will be getting a trans temp guage soon as well.
I know the 4r70w calls for Mercon V, not regular Mercon. My question is can I use a high quality synthetic like Mobil One, Redline, Royal Purple, etc...? Or am I best sticking with a standard Mercon V fluid? I want to put the best stuff I can in there because I understand how important it is to keep trans temps down and how easy it is to ruin one. My second question is how much fluid do I need? I plan on dropping the pan first, and then disconnecting the return line to the trans cooler and performing a complete flush until I start to see clean fluid coming out.

Thanks for any input
Brian

 

I went with the Motorcraft fluid for my 02. Good enough for me.

Adrianspeeder

 

My 98 5.4 takes 12 quarts when I drain the converter too. I don't remember what the cut-off year was but you might have a plug in your torque converter. Draining that and the pan means you don't have to pull the return line and "flush" the trans.
I was under the impression the Mercon V designation meant it was a synthetic blend as compared to conventional Mercon. I buy Aamco (made by Exxon) Mercon V from Strauss Auto when it's on sale and the label says "synthetic blend".

 

As long as it says Mercon V and not Mercon/ Dextron 3, the manufacturer doesn't matter. However, it is hard to find outside the Ford parts store, so I've only gotten Motorcraft Mercon V. I think the cut off for having a converter drain was mid year 2002 so check it. Even without draining, getting as much as you can plus filter should be fine. You're probably looking at no less than 12 quarts, maybe 11 so plan for that.

 

2001 was the last year with a drain plug in the TC. So in his case, it is a flush or multiple pan drains.

 

You were impressed wrong.

MERCON V is a specification. There are fluids on the market that meet MERCON V specs that are dino fluid, most are synthetic blends, and there are also full synthetics that are MERCON V.

The same can be said for MERCON fluids. There are dino, blend, and full synthetic MERCON fluids available.

ALWAYS use a fluid that has a MERCON V rating in a 4R70W. Bad things can happen if you don't.

 

So I won't be able to use something like Mobil 1 ATF? I guess I'll just stick with the standard stuff in Mercon V.

 

Mobil 1 recently changed their formulation. It's now MERCON and MERCON V rated.

 

I ended up getting 12 quarts of Mobil 1. Like mentioned, it says on the bottle that it is now rated for Mercon V, and was only $1.60/quart more than the Castrol. I wanted the good stuff because I do work the trans hard when towing, so I'll feel safer this way. Now I've just got to go change it. It will be a messy job...

 

FYI update...

I dropped the pan (ATF shower too) and cleaned it and the magnet. Replaced the filter, and buttoned that all back up. I then poured 6 quarts in, disconnected the return line form the trans cooler, and started the truck up. I did this procecudure several times, adding and then flushing about a quart at a time. All in all I added 12 quarts, but the fluid level is not even high enough to register on the dipstick yet. I was expecting the fresh fluid to look much cleaner coming out the return line, but it all looked about the same. I probably ended up flushing more than was necessary, but at least i know it is flushed well. I'm going to go get another couple of quarts and then test drive later today. I hope all goes well, as I am starting to have second thoughts about the multi-type approved Mobil 1 ATF. Stay tuned.