Oil for Columbia rear end

[1stford]

I have a Columbia rear end and have been doing some reading about the oil to put in it. Seems there are a lot of opinions on this subject of should rear end oil be GL4 or GL 5, but wanted to know what everyone else is using. I bought this Valvoline gear oil and it looks like it's a GL 5.

I did just order a GL4 from VP racing for the transmission as it seems GL4 is the only way to go for top loaders.


https://shop.valvolineglobal.com/pro..._BwE&Size=1+QT