5hp24 transmission no reverse

[bdriven]

Hello friends,
yes, still me, with another tranny thread, this time, I do believe I found my problem.....hopefully.....so here's the situation, I did my own rebuild, both tranny, and valve body, put it back together, and the reverse works, but only cold, after it gets hot, or I drive it for about 20 minutes or so, reverse will not engage, so I figured, replaced everything on it, so it has to be the ATF I used.....as I read deeper, realized, that the valvoline I used, differs a lot from what I should've been using (valvoline reads that @40C, 28.1 viscosity, @ 100c, 6.11 viscocity), whereas the recommended for ZF tranny is @40c 38, and @100c, 7.1. now, would you guys think, that this difference, would cause the reverse slipping?
thanks in advance for your thoughts !!