I found this to be edumacational on gear oil selection, with real reasons behind it, not just “synchromesh is da bomb” (but could be totally wrong for your car). Info is for Mitsu tranny’s but also is just educational for all vehicle makes
http://www.teamrip.com/manual_transmission_gear_oil_recommendation_info.html
Be careful using the Synchromesh and the Redline shockproof people