Ooops, mixed tranny fluid, what now?

I think that you will be alright. Look at both bottles side by side.

I would venture to say that FORD uses one because of a contract and that is why they say not to use the other. I could be wrong though.

If it is an automatic, you will need to drop the pan, change the filter then re install the pan.

OR take it to a shop that can do a good flush but will cost 100+ bucks.

Define "some". How much dextron did you put in?

I wouldn't worry about it. The tranny will probably run fine, since it's still mostly mercon. If it really worries you, you could change the fluid, but I wouldn't sweat it.

the Mercon V is different friction qualities that makes it work better with the 4R70W transmission. if its not a lot i wouldnt sweat it. do you know when the transmission was serviced last?

i wouldnt just get a flush. just doing a flush at a dealer or a jiffy lube type place is an incomplete service. they dont change out the filter. you wouldnt change your oil without changing the filter would u? if you want to do it yourself, get some mercon V, pennnzoil makes some, but i dont recommend that because pennzoil products are usually crap. i use either valvoline, motorcraft or amsoil. you will want about 16 quarts. safely raise the vehicle up, and drop the pan. when the pan is out clean it, and replace the filter. there is a stock 4r70w pan with a drain plug in it to make future trans services easier. it comes on the E-series vans and other such applications. i think it was about $60 from fordparts.com. back on topic, there is a plug on the bottom of the bellhousing, take the plug out and turn the motor over till you see the drain plug in you torque converter, let that drain, it should take about 20-25 minutes. put the pan back on reusing your stock gasket. (there might be a little white or yellow bobbin bouncy ball looking thingy floating in the pan. take that out and throw it away, that was from the factory where they plugged the dipstick hole.) lower the car and fill it with as much fluid as you drained. run the motor after your have added about 5 quarts. keep checking the dipstick with the trans in park.

there is an execellent writeup on www.crownvic.net the CV's use the same trans as the mustang so everything applies.