Though I'm not sure how many on this forum actually use Texaco Havoline ATF, this AMSOIL commissioned test gives credence to those recommending regular transmission fluid changes:
AMSOIL vs Havoline ATF Viscosity Testing (http://www.c66racing-synthetics.com/TestResults/MerconVATFtest.htm)

The Texaco fluid doesn't appear to be able to hold up for a 100k mile change interval. :cheers: