Transfer Case oil

[fritz]

Hello ,Can someone tell me the proper oil for a 1960 4x4 t case? I have heard that the correct oil is 80 wt. Mineral oil? If so where would that be found? If Mineral oil is correct I am curious as to why mineral oil would be the correct type.

Thank you,
Fritz

[FetchMeAPepsi]

Mineral oil is pretty common to use in gears back in the old days, but today we have synthetics and cleaner refined oil and you can get longer lasting performance from those.

For my 4x4 transfer case, after much researching, I went with Red Line 75W90 NS GL-5 Gear Oil ( #58304 ). It takes 3 pints IIRC. Sticks to the gears better than any mineral oil and stays protecting even if you've let it sit for a while. And heat don't bother it at all.

[fritz]

Thank you for your reply best advice I gotten! Would you use the same for the transmission?

Thank you,
Fritz

[FetchMeAPepsi]

Thank you for your reply best advice I gotten! Would you use the same for the transmission?

Thank you,
Fritz

Yes, i use the same in the transmission. In the pumpkins I use 57904.

[fritz]

thank you for your reply!

[James]

Thank you for your reply best advice I gotten! Would you use the same for the transmission?

Thank you,
Fritz

I suggest you get the oil for a synchromesh transmission.
Here are some options:
https://www.summitracing.com/search/department/oils-fluids-sealer?N=4294950702&SortBy=BestKeywordMatch&SortOrder=Ascending&keyword=synchromesh

GL-5 oil has sulphur in it, GL-4 is worst. It will eat up the synchro in the transmission, I read it can happen in as little as 100 miles.

[FetchMeAPepsi]

Good point James, All the oils I recommended are non-sulpher oils because you have brass synchros in some of our trannys and we want them protected.