3 speed gearbox oil

[Ianrhall]

I want to change the oil in my old truck, has the 3 speed floor shift box.
How much oil will I be needing?
Thanks
Ian

 

[rheltzel]

2 1/2 pints. I use 80w-140. Fill until just below upper fill hole on side of ******.

 

[30-9]

I used Gl1 (very important) weight is personal preference I used Napa 90wt

 

[JSeery]

GL-1 or GL-4 I would go with the GL-4 it has much better gear load protection.

 

[flatheadmurre]

Just check that the oil is redmetal safe if going for a higher API rated oil.
A lot of the modern oil additives are designed to work with redmetals, if not your syncros will be harmed.