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Good afternoon, boys and girls

I've had a good look through the tranny fluid posts but none really answer my question.

I believe these 4R70W boxes call for Mercon V.

Trouble is, trying to get hold of Mercon V in the UK is STUPIDLY expensive.

Does it absolutely have to be Mercon V or will something like Dexron III (I know, putting GM stuff in a Ford...urgh) work?

Or is there a suitable substitute for Mercon V, other than dexron?


Also, is it imperative that I drain the torque converter too, or will swapping the fluid in the pan and the filter suffice?

Obviously ideally the whole lot would swap, but if 4-5 quarts are required instead of 14, and it must be Mercon V, that will reduce costs significantly.


Thanks in advance
 

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It's almost 14 quarts(which includes the torque converter) of Mercon V is what the trans calls for. You can't use Dextron unless you want it to shift like crap. Mercon V isn't cheap here in the USA either($8 to $10 USD a quart). If you buy two 5 quart containers then that will save a bit and then 4 separate quarts.
Changing just the fluid in the trans is the bare minimum but you should really drain the converter as well especially since it seems to hold most of the fluid. Only doing the trans pan would just dilute the old nasty stuff a little with fresh fluid.
This should be the rubber plug to get to the converter drain. You have to turn the engine until the plug is accessible thru the hole.
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Good afternoon, boys and girls

I've had a good look through the tranny fluid posts but none really answer my question.

I believe these 4R70W boxes call for Mercon V.

Trouble is, trying to get hold of Mercon V in the UK is STUPIDLY expensive.

Does it absolutely have to be Mercon V or will something like Dexron III (I know, putting GM stuff in a Ford...urgh) work?

Or is there a suitable substitute for Mercon V, other than dexron?


Also, is it imperative that I drain the torque converter too, or will swapping the fluid in the pan and the filter suffice?

Obviously ideally the whole lot would swap, but if 4-5 quarts are required instead of 14, and it must be Mercon V, that will reduce costs significantly.


Thanks in advance
Yes, you have to use Mercon V but, Valvoline makes a product called MaxLife ATF...

MaxLife™ Multi-Vehicle ATF : Product Catalog - Valvoline™

To become designated "Mercon V", the fluid mfg must submit to several 3rd party tests and then submit to the vehicle mfg to be able to use the "title", The techs at Valvoline are really good and when they came out with this almost 15+ years ago I called them and spoke for almost an hour on this.... I have used this ever since in both vehicles I have with no issues (they both have the 4R70W)..... the oldest is a 1997 Merc Cougar Sport (V8)..... it shifts very nice....

another potential option is Motorcraft Dextron V semi-syn... it is much cheaper than most of the Mercon V....and is of very, very good quality!!!!!!

Amazon.com: Motorcraft XT5QMC Mercon V Automatic Transmission Fluid - Case of 12 Quarts: Automotive
 
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