Ford HD4R100 Fluid.

[Big Bore]

Not sure exactly where this belongs but the transmission came from Ford so not really aftermarket.

Got a Ford built HD4R100 several years ago, just recently installed it. Tag says Mercon V, but reading around there's all kinds of "don't use Mercon V" etc. I wouldn't even have thought about it but my buddy said there's some issues with Ford trans fluids recently. Trying to research the issues just produces more confusing and contradictory information. Anyone know what the straight dope is? Thanks!

 

[Mark Kovalsky]

Ford wouldn't know the correct fluid to use in their transmission, so don't believe the MERCON V tag. Always believe what you read on the internet above the company that makes the product. [/sarcasm]

How old are the things you read that said don't use MERCON V? Before 2006 MERCON V didn't play well with the 4R100. In 2006 Ford changed MERCON V and dropped MERCON, which is what the 4R100 used to use. The newer MERCON V is the correct fluid for the 4R100.

 

[Big Bore]

Thanks Mark, I actually read your comments to that effect in another older forum elsewhere after making this post and doing further research. I already topped it off with Mercon V and I'm confident it's fine. Appreciate your continued contribution to posts like these.
To the question, the age of the posts ranged roughly from 2004 to 2016. It looks like the confusion starts with using Mercon V in the older transmissions as you pointed out along with the later model fluid issues and all of them being kind of mixed together but I managed to unravel it, with the help of your aforementioned posts elsewhere.

 

[Mark Kovalsky]

I used to post not to put MERCON V in a 4R100. It did cause problems. When Ford reformulated MERCON V they should have given it another name.

 

[Big Bore]

Thanks again for your replies, I have put about 600 miles on it in the Colorado Mountains and I would say this tranny is performing just as good as the $5000 pulling tranny it had before I blew the forward/reverse gears out of it breaking through a snowdrift (I'm pretty sure you diagnosed that when I posted the issues). Lesson learned. Very happy with this Ford built trans so far. I'm pulling a trailer across country this week and I think I'm going to have it professionally flushed after the trip just for good measure. Cheap insurance and piece of mind.

I cant help thinking of the movie Vanishing Point when I see your name btw. lol