here is a post in transaxle:
"My Synchros aren't so great. My biggest problem has been the 1-2 shift, it used to crunch a little when the temps outside were 40 or lower.
Based on advice I got here at CEG, I had been running ATF+3, dino. It was doing pretty well. For the money it was the best fluid I have tried. I think it was starting to break down (shifts getting harder when cold) and so I decided to try a different fluid.
I replaced the fluid with Royal Purple SynchroMax a few days ago. After a few cold days of driving (right around freezing) I can say my transmission is shifting easier, and synchros are behaving better than they have in probably the past 30-40k miles. I am VERY pleased!
I won't make a blanket statement, but, for MY car and for the Cleveland climate, Royal Purple is the best fluid I've come across.
From my trials, I would rank them like this:
#1 Royal Purple (easy shifts, no crunching into second)
#2 ATF+3 (Quaker State dino) (shifted easily, occasionally crunched)
#3 Redline MTL (shifted easily enough but crunched too often while cold, even though I had added FM)
#4 Factory Fill (hard shifts, crunching when cold)
#5 Ford Honey (unbearable. to go into 1st, car had to be at a complete stop, then i had to double clutch. never did 1-2 in the first 10 minutes of driving, had to go to 3rd. )
Brian "
