Is ACDelco 10-4033 transmission and transfer case fluid suitable for a SM420 transmission built in "I"1355. Sept13, 1955. It does have brass synchros. I have seen it listed as 75W80 and also 75W90. It seems thinner when poured at 60 degrees F. I have seen it listed as mineral oil. I am not sure if it is GL-4 or GL-5 altho it has been alluded to being GL-4. And it is reddish in color.
It appears that the old Dexron III is listed as GL-3 even tho I have not seen it for sale - I do not know if this is true.
Last edited by 42465967; 02/12/20223:47 PM. Reason: words
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
Last edited by Dusty53; 02/12/20224:21 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."
Is ACDelco 10-4033 transmission and transfer case fluid suitable for a SM420 transmission built in "I"1355. Sept13, 1955. It does have brass synchros. I have seen it listed as 75W80 and also 75W90. It seems thinner when poured at 60 degrees F. I have seen it listed as mineral oil. I am not sure if it is GL-4 or GL-5 altho it has been alluded to being GL-4. And it is reddish in color.
It appears that the old Dexron III is listed as GL-3 even tho I have not seen it for sale - I do not know if this is true.
Fluid is too slick for syncro to work. G.M. sells manual transmission & transfer case fluid p/n 88861800 which is Dexron II in a new package. Dexron II became Dexron llE which was became Dexron III. ATF is not the thing to use, HRL is spot on.
Last edited by BC59; 02/12/20224:51 PM.
BC 1960 Chevy C10 driver 261 T5 4.10 dana 44 power loc 1949 GMC 250 project in waiting 1960 C60 pasture art Retired GM dealer tech. 1980 - 2022
Well, tsc says it is not deliverable and not available in the stores around here. And they list it as GL-1. Not sure that makes any difference. Oscheln does not have anything like it. Life is good, somedays are better. 8-)
