It has been suggested by many others that the full mineral oil is the best for use in the SM420. Its what I use. Its available at Tractor Supply Company and possibly other outlets. Do not use it in your rear differential.
I've included the MSDS for the 10-4033 Oil which is showing that it is a mineral oil with some antifriction additives. I don't think it would cause any problems if you use it.



Ron
Attachments
IMG_2338.jpg (45.41 KB, 100 downloads)
10-4033 acd gear_oil_75w90_select_premium_semi_synthetic.pdf (161.37 KB, 4 downloads)

Last edited by Dusty53; 02/12/2022 4:21 PM.
Ron - - Dusty53
1954 Chevy 3604
In the Gallery Forum
"You can't dance with the Devil and then wonder why you're still in Hell."
"They will forget what you've said, and they will forget what you have done but they will never forget the way you made them feel."