John Deere Hygard hydro/transmission fluid?

My buddy used it in his 8 in. He said that it tightened it up off the hit and held it better in the top end. 2/10s and 3 mph faster. The converter was too small for the weight of his car. 4100 lbs. and didn’t couple properly. 2 liters of dexron to color the hygard. Kim