SKarpenz

My 85 GSL-SE grinds when putting the trans into 5th gear when the car is warmed up (hot). If the car has just been started and I'm driving it, it goes into 5th quickly and quietly. I ordered some Redline 80w90 for the trans and diff, think this will make a difference? I guess the grind isn't a big deal, I just found it strange as usually my cars have done the exact opposite in hot/cold engine conditions. Any insight would be nice (and is always appreciated). I searched, but no luck.