I just recently installed my complete setup consisting of LQ4, frt mount 76mm, 4L80E swap with a circle d 258mm billet TC, and 261xhd internals in my stock t-case housing...
A local shop (Cooks Racing in Cowpens, SC) built my 4L80E to the MAX and he specified a 50/50 mixture of ford Type F and Castrol Super Blue Hydraulic fluid... It took 12 qts for a fresh rebuild and a new TC. I specified approximately a 3400 stall converter from Circle D. What I have found with this fluid, is extreme streetability... believe it or not it drives like a stock truck almost, and the extremely hard shifts are NOT felt, until you get in it pretty hard. ZERO torque management and the stiffest springs and valve body mods possible in the trans. The beauty of all this is at only 5-6 psi, it stalls up to approx 4100-4400 depending on temperature and after 5 back to back 4x4 passes and very hilly driving to and from the track, the fluid temp hasn't been over 135 degrees!!!! Even after a long brake stall on the last pass waiting for the D***head in the left lane to realize what staging lights meant.... The fluid is obviously much thinner and lighter weight than dexron, and Castrol Super Blue is extremely temperature stable and absorbs heat easily and dissipates it fast as well. Its a low surface tension fluid thats on the thin side, hence the Type F to thicken it somewhat. But it contains NO teflon or other slippery crap like the new dexron 6 and other synthetic fluids which give your clutches and other friction materials something else to deal with to harness the torque. I can provide a video proof of the driving charachteristics and stall speeds at only 5 psi. 10+ will put it about 4800. Which is awesome for Full boost 4wd launches, yet for some unknown reason provides excellent street manners as well. I have read and been told elsewhere that this was TRACK only stuff and was taboo on the street. Why i don't know when it works so well and the man building my trans specified it.

Just figured i would let you all know what i have found using this mixture... it may be worth a try to some to see if you have the same results. It certainly is cheap enough at $50 a five gallon bucket. They ONLY sell it in 5 gallon, 30 gallon, and 55 gallon drums. And my case of valvoline type F was $43.

If anyone else has used this, please let me know of any failures, problems, or positives.