Tremec 3650 fluid type ??

[3yearplan]

For those that have this transmission or just have some knowledge to share any help would be appreciated. This question refers to a 2004 trans. What fluid is recommended ? The forums (Mustang) are all over the place. Even Tremec themselves are a bit misleading. Regular Dex 3/ Merc. to Mobil 1 full synthetic to GM/Pennzoil Synchromesh. I've read so much about each, pros and cons, blah, blah, blah. What do the people on HERE know?

Thanks in advance, Mike.

[Jim1855]

I like and use Red Line MTL. Have used Dexron and Royal Purple SyncroMesh. I've never noticed huge differences. Lots of opinions & options. Have also heard that running a little (maybe a third or half qt) low makes shifting easier or faster. My trans is a 2004 TKO-600 rebuilt by Liberty Gears with all of their upgrades.
Jim

[CraigS]

I have always used the GM Synchromesh in my TKO500. But 2nd gear synchro is getting a little weak so a couple of months ago I used 2 qts of Pennsoil Synchromesh and the last 3/4 qt 75-80 synthetic trans oil. This helped the 1-2 shift.

[3yearplan]

Thanks guys. It's a 78,000 mile trans so I'm not too worried about it, but was just wondering what to stay away from.