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As far as I know, the service manuals call for "Mercon" transmission fluid.
Unless I'm mistaken, Mercon is a type of ATF. There are "Mercon V" and "Dex/Merc" available locally and they both meet the Ford specification.
I tried Dex/Merc, it seemed to make shifting smoother. Wasn't sure if changing out the old dirty unknown transmission fluid (@180k miles) from the previous owner and simply replacing it with fresh is what loosened up the shifting.
In a continuing effort to flush/clean the transmission, I then tried Mercon V (@190k miles). The shifting became slightly harder to get from one gear to the next.
Now after two transmission fluid changes (in 20k miles), I'm satisfied that the transmission is "clean" and I'd like to put some proper fluid in there that will stay for the next hundred thousand miles or so.
So far I've been using Napa/Walmart cheap cheap cheap fluids just to flush/clean everything out.
Which of the following fluids would you recommend I put in my ZF6 manual transmission? I might be able to find something else if I shop around or special order, but these three are available locally with a simple trip to the part store.
Any advice? Requirement is 5.8 quarts, so this won't be cheap and I hope I don't have to change this fluid for a very long time.
I checked the manufacturer website for all three fluids and unless I'm misunderstanding something --- all three are listed as proper fluid for this transmission.
Use any ATF that's Mercon V of Dex/Merc. I've used both. I've used synthetic too, but didn't notice any difference or improvement. Now I'm not in a cold climate, so if you are the synthetic might hold some value. For me I just use the cheap Dex Merc and add a little synchromesh to it to cut down on the gear rollover sound and smooth things out a little when warm. When cold it makes it harder to shift, but I'm in Texas so we don't get too cold.
I've got 530,000 miles on my factory 2002 ZF-6 and all I've done is change the fluid every 50,000 miles and changed the clutch twice.
And if you think 6 qts of ATF is expensive, try changing the fluid on the automatic.
^^^^Could you be a little more specific when you say "synchromesh"?
Also wondering. How often do you start your truck and find yourself unable to slip into first/reverse gear without letting the clutch up and down a few times, or having to slip into third or fifth gear before being able to shift into first gear and get moving?
Also wondering. How often do you start your truck and find yourself unable to slip into first/reverse gear without letting the clutch up and down a few times, or having to slip into third or fifth gear before being able to shift into first gear and get moving?
All the time or just when cold? The synchromesh or dino ATF in really cold weather can make it a little difficult to get into first.
Worn clutch hydraulics can do the same thing. I've had a slave cylinder that was so bad I could barely get it into first no matter what I did. Went from a little difficult to oh heck now what in 2 days. A new, pre-bled clutch hydraulic kit fixed that issue.
I replaced my clutch master/slave assembly not long ago. Also inspected master cylinder pushrod bushing recently and didn't see any strange wear or damage.
No cold climates here, I'm in hawaii. Never goes below 70*F where I park.
Thanks for posting the link, I'm going to think further on this and I'll probably have another question or two before I buy fluid and change it (hopefully for the final time.)
11-30-2015, 03:18 PM
