[Nomadic_Dragon]

I recently put a transmission cooler in my Gen 4 taurus, and noticed the fluid was pretty dark. So after deciding not to have a lube/oil place charge me $132 for a flush and fill, I did it myself. I think I might have messed up, though...I couldn't find enough Mercon V even after buying from two local stores, so I bought 3 gallons of Mercon III to do the flush with, which I did, dropped the pan and replaced the filter, then filled with the five or so quarts of Meron V that I had, letting Mercon III flush from the tranny as I added it. Fluid level is good, but now the car 'feels' heavier, and I've certainly dropped a second on my 0-60 time. Should I take it in for a flush to get rid of all possible Mercon III in the tranny, or what?

 

[diesel600]

You should only be using mercon V, mixing is bad. Now you need another complete flush with ONLY mercon V. You should have waited to get more of the right fluid or just paid a shop to do it. Now it's probably gonna cost even more. Remember your tranny holds like 12 quarts, and you only have 5 of the right kind in there. Go the flush done soon, don't drive much until you do, and pray that no damage has been done.

 

[93taurusSX]

Ditto. the viscosity and other chemical properties of Mercon V are sufficiently different from Mercon III that interchanging them will cause bad performance from the tranny made specifically for each type. Get the flush done ASAP. Might want to change the filter too since it'll be saturated with some Mercon III that won't be readily flushed out.