mixing mercon III and mercon V?

[brinker88]

Want to do a tranny filter change to the truck before winter (see sig for details). I want to drain the torque converter and refill with tranny fluid I have on hand (B&M trick shift mercon V). Will there be any ill effects on mixing the stock mercon III fluid with this higher grade?

[azgilamonster]

from what I have been told by many mechanics is you can go up but you can't go down.
in other words if your truck calls for type II or III you can use V but if the vehicle calls for V you HAVE TO USE V nothing else

hope that helps,

[brinker88]

all the info I needed. Thanks