Howdy folks!
Long story short, I am looking for
specific and up-to-date recommendations for gear oil in an original 3-speed inside my 48 Stylemaster. I have the manual which recommends 1& 1/2 Pints of 90W "Transmission or mineral oil lubricant, or all-purpose/universal gear lubricant."
The only thing I have been finding online is decade-old conversations about how GL-5 is bad for the brass, and that GL-4 is what I want. The problem is, I am not finding GL-4 really anywhere. I have been calling around and discussing with some of the local folks I know who have knowledge of these sorts of cars and they are mainly recommending things like this...
https://www.napaonline.com/en/p/RPO01300?impressionRank=6which do indeed have very specific information about how they are a substitute for GL-4 and GL-5 (Strangely) and are safe for yellow metals like brass.
Thoughts?
Side questions:
Pulling the plug off the rear-diff and transmission (filler plug), at what level should the oil be when cold? I have been told an inch below the bottom of the plug for both (Again, transmission filler plug). Sound about right?