Does it matter if you use GL4 or GL5 gear oil for Tacoma manual transmissions? Ive heard that using GL5 in Toyotas can make your synchros slip making them wear out faster, but that might just be with the older trucks. If I go with a GL4 I am going to run Redline MT90. My 98 Tacoma manual recommends GL4 or GL5 so just wanted your input.

 

I prefer GL-4 oil in all my manual transmissions:

[url]http://www.4crawler.com/4x4/index.shtml#SyntheticGearOil[/url

Its not so much the GL-5 wears out the syncros, its that it is too slippery and makes them spin/slip longer before matching speed and allowing the gear shift to happen. So a good GL-4 oil will provide faster, crisper shifts. A good synthetic GL-4 oil will also help with low temperature shifting performance.

 

I just changed out mine with the MT-90 and removed the stock spring that was squeking. Feels much better now.