I just recently put a 93 gsr ys1 trans in my car and i need to add trans fluid and a lsd additive. Can anybody tell me what the best thing/ratio is? i use royal purple motor oil so naturally i would want to use the gear oil in my trans but the lowest grade they make is 75w90, would this work or not because it is synthetic? Any help would be great.

 

royal purple synchromax, redline is good too