This thread is old, but in trolling for info on ATF+(whatever) VS Dexron (whatever) in Dodge trany's; I ran across it and can't believe the mis-information it contains.
First up, a simple call to 'an un-named manufacturer' (the person spoke from anonymity because of Licensing (see 2 below)) resulted in MS-9602 - M5040901 - GMN-10060 the specifications for ATF by 'the big three' and a comment that there is not really a dang bit of difference in any of them, except for the new Dexron VI (see below).
Second, Dexron(R) / Mercon(R) & Type F(R) / ATF+ or ATF Plus(R) are all COPYRIGHTED specifications that oil companies MUST pay for the right to put "Compatible" or "approved" on the label of their products. Of course those copyrights are owned by, go ahead and guess - thats right; Chevrolet, Ford, and Chrysler (respectively). This was admitted by that un-named company not listed above.
Third, ATF+4, Dexron VI, and Mercon V are all FULLY SYNTHETIC oils; they have to be because of reason 4 below.
Fourth, OIL is OIL - it don't matter the name you put on it, as long as it meets certain specifications (ASTM "kinematic viscosity of oils" Specifications in this case). Those specifications are (in no particular order) Gravity (or weight), Viscosity at a given temperature, and heat dissipation.
Now in looking at the previously mentioned ATF's, the ONLY difference is the viscosities at given temperatures, are:
Code:
Type | Viscosity | @ 40C | @ 100C
ATF+4: V204, cST@40C 33.24 cST@100C 7.51
MercV: V205, cST@40C 33.20 cST@100C 7.50
DexIII: V201, cST@40C 34.70 cST@100C 7.70
Type F: V150, cST@40C 36.00 cST@100C 7.20
DexVI: V145, cST@40C 29.50 cST@100C 5.83 *1
Amsoil: V168, cST@40C 38.90 cST@100C 7.60
RoyalPurple: V210, cST@40C 32.50 cST@100C 7.50
Redline syn: V197, cST@40C 32.50 cST@100C 7.20
Redline C+ : V213, cST@40C 32.30 cST@100C 7.50
Redline Race: V177, cST@40C 53.70 cST@100C 10.00
So what does all that mean? It means that the differences between any of these ATF Fluids is negligible with the exception of Dexron VI (IE: they all work in any trany) the
only thing you will notice is a small change in the shift points and or hardness in the shift; because of how thick the fluid is at any given temp. Notice that "Race" fluid is "thicker" at higher temps, and will give you a harder shift.
Note 1: GM Intentionally made Dex VI non-compatible with other fluids - IE: Don't use it in anything else because it is way too thin.
Note 2: We used to use Type "F" in the Powerglide & TH350/400 & 727TF to improve the shift (before all the fancy race fluid's came out).
In closing, and with all due respect to everyone's opinion on the matter: The laws of Physics (Hydrodynamics) are not influenced by opinions. Because transmissions operate from a well known set of laws, and within a wide range of tolerances - the difference between one fluid and another in any given transmission would still be well within spec's.
