I recently changed out the
AMSOIL ATF I had put in my 06 CTS-V daily driver to put in the
AMSOIL Torque-Drive Synthetic Transmission Fluid (ATD).
In doing so, I noted that the sample results indicated the AMSOIL ATF was completely shear stable over the 6300 miles of use I had put on it with its viscosity remaining at 6.8 cSt at 212F over the life of the sample. Although this is pretty much what I'd expect, what is more alarming is that the stock Dexron III had sheared down from about 7.3 to 5.0 cSt over only 10k miles of use.
2006 Cadillac CTS-V Used Oil Analysis Dexron III vs AMSOIL ATF Transmission Fluid
For those that still have the stock fluid in your car, this should give you pause.
Note: The reason I swapped out my perfectly good ATF for the ATD takes some historical perspective. AMSOIL's ATF used to have a hot viscosity of about 7.3 making it very similar in viscosity to Dexron III. AMSOIL listed the ATF as their primary recommendation for our trannies, with the ATD as the alternative. I've been using the ATF in my Vette and CTS-V for years. But, about 18 months ago, they lowered the viscosity of the ATF down to 6.8 and labeled it for use for both Dexron III and the newer, lower viscosity Dexron VI. I queried their director of gear lubes on the suitability of the lower viscosity ATF for our trannies. In response, they re-evaluated their recommendations and swapped them, listing the ATD (at 7.4 cSt) as primary and the ATF as alternate. Interestingly, this month they raised the viscosity of the ATF back up and it is now 7.6 cSt, removed its recommendation for Dexron VI, and came out with a new fluid (ATL) for Dexron VI applications.
