What fluid for a 4-speed trans?

I read that too. That's why my Ragtop just has 75w-90 now.
I'd like to say that when I hurt some synchros ..that it was one of two things...switching to 90w... it the non performance pedal set and very quick shifts with it... but eventually it started grinding here n there and then it didnt slide right into gear, it need more force...you can feel the engagement as where you didnt before. Been 10 yrs like that. ..now I have a kit and will change the synchros and input bearing.