Type F is fine for 3 speed autos, where top gear is a 1 to 1 ratio and no planetaries are changing a ratio. For overdrives, type F doesn't have the extreme pressure additives needed for extended overdrive planetary operation. That's where Mercon/Dexron comes in.
Type F has a little more "grip" to it vs. other fluids, but if you want your overdrive planets to last for the long haul, stick with Mercon/Dexron.
As far as tractor hydraulic oil goes, check out this big thread here:
http://www.theturboforums.com/smf/in...?topic=58907.0
The general consensus from the forum seems to lean toward the John Deere Hy-Gard oil which is rated for use with internal wet brakes, which happen to be very similar to auto transmission clutches. Case also makes an equivalent tractor fluid. Some guys in the thread that switched to the JD oil reported a whine at first startup when cold, which indicates pump cavitation. Once warm, the oil thinned out and the whine went away.
I had a customer a while back with a 4L60E that tried the local parts store tractor fluid after I just freshly rebuilt his trans. That experiment didn't last long due to the transmission temp running a hell of a lot hotter. Upon teardown after this experiment, I found the front vane pump had evidence of starving/cavitating. Of course, vane pumps aren't known for their suction capability like a gear pump has. On top of that, the 4L60E uses a dacron/cloth filter media which filters better, but is also more restrictive than an old school transmission metal screen type filter. This combo of a vane pump and a cloth filter definitely worked against the tractor oil working in this platform.
There is also a mention in the thread of a lower viscosity JD Hy-Gard that is very similar to the viscosity of regular ATF and is recommended for lower temperature operation in farm equipment. If anyone here is sitting on the fence about trying tractor fluid, especially in a trans that uses a dacron/cloth filter, I would give this lower viscosity JD Hy-Gard a try first. The cost of the JD oil if very reasonable, too, as most folks seem to be getting it for about $60 for 5 gallons.
Gear pump transmission list: Powerglide, th400, th350, 4L80E, C-4, C-6, FMX, AOD, 4R70W, E4OD, 4R100, 727 Torqueflite, 46RE, 47RE, 48RE.
Vane pump transmissions: 200-4R, 700-R4, 4L60E.
One of the posters in the thread was someone from Hughes Performance, who have a lot of high power automatic trans experience. They speak very highly of the Lucas Sure Shift fluid. They rate Castrol brand type F a close second. They also have some interesting info on avoiding full synthetic ATF. They mention the JD Hy-Gard, too, but mention some planetary gear teeth spalling in glides at the 2000hp level with it.
