i'll suggest to choose fully synthetic 75/90 or 75/85 or better if chosen per manual.
as the engine is in good condition, so don't go for thicker oils. Otherwise the gear will become harder and driving pleasure will be lost.
the gear oil of all companies are good. chose anyone like Zic, Kixx, PTT, etc. all these gear oils are good. I'll not suggest to choose Honda or Toyota's gear oil. Other companies are far better.