For the last 12yrs in our eight 1998 to 2004 GG bikes we have run a 50/50 mix of ATF and T6 or Delo truck oil in the trans and it works perfect and it is cheap if you buy the big container of the truck oil. I think ATF is too thin
We run Klotz R50 if we are riding fast with lots of wide open areas and we rund Klotz Supertechniplate for general trail riding. I spoke with a Klotz engineer and he told me it was ok to mix the two Klotz oils/fuels which we regularly do since our riding changes from trip to trip.