Technical Saginaw 4 speed lube

I'm dropping a used saginaw4 speed into my 63 C10. What is the proper/best gear lube.
I've read the gl5 may be harmful to the brass parts.
Thank you as always

 

90 weight gear lube. as far as brand name, go to oriely's ask which one they sell the most of.
been looking for a Saginaw for 6 months..lucky rascal......

 

I'd stay away from the GL5 and synthetic gear lubes in an older model transmission. They're formulated for newer trans that use composite faced blocker rings and they work well for that purpose. But in many cases they provide so much more lubrication that the older style brass blocker rings can have a problem getting a grip on the synchronizer hubs. The stuff can just be too slippery. The result can be a balky shifter and a trans that feel like it needs new synchos.

90W gear lube should work fine, and some older specs called for 30W motor oil for easier cold weather shifting.

 

Syncromesh for 4 speeds. By Royal Purple.

 

can you still find GL4 at your local parts store?

http://www.napaonline.com/Catalog/C...ive-1-GAL-CRC-85W90/_/R-SLRSL24239_0006410049