trans fluids

[hstlr21]

What's up guys first time on this site . Quik question i bought a 1990 Lx 5.0 that's been in storage sinse 1997 with 60.000 miles so i've been going through the car fixing allitle of this and that . i've changed the rear end fluid w/slip additive (redline 75-90w synthetic) and i changed the trans gearbox fluid .The book say's this car should use ATF,so i did synthetic ofcourse. I've heard you should use like 5w-30 synthetic motor oil , does anybody have any feedback on this matter i would really appriciate it.( sinse i've changed the fluid the shifter feels more mechanical and you can't shift the car quick with out grinding allitle for about 10-15 min. That's what made me think the prior owner was using a synthetic. THANKS JIMMY.