221 Lube

[Short 3/4]

Awhile back started using Redline MT90 in some other vehicles of mine that were having hard shifting issues. Was really impressed with the results. While I have no problems shifting the 221, I figured maybe it would stand up better to the high heat that box generates. I’ve always changed out the diff, trans and xfer 90w fluid in all my old junk every two years and never had to top them up between. I decided to check the level the other day when I was under there and after 6 months the darn case was almost dry. I guess those seals don’t even slow down that synthetic lube. I’m thinking of trying 140w. I suppose that would be more heat resistant and might even run a little quieter.
What are the rest of you running
Tom

[kwmech]

90 wt gl-4 dino oil