What weight gearlube in the TCase/Diffs?

[Niki]

I already changed the rear diff, threw in some 75W90 I had laying around to clean any gunk out. Now I'm going to change to synthetic in both diffs and the Transfer case, the manual just says hypoid gear lube for the diffs, and 80W90 or 80W140 for the TCase. My truck is empty 90% of the time, the other times maybe a 5-6K# trailer or 1k# in the bed. Is 80W90 too thick for Chicago winters? Because that's what I was going to use, and don't want to have to change it again before winter. I already have 10W40 in the getrag, probably going to change that to synthetic. -Nick

 

[bgilbert]

75w90, 80w90 80w, 90w whichever you like for the diffs and t-case. 80w140 would only be needed if you really worked the truck, gross weight often etc. Your t-case might not like synthetic. It might find a hole in one of your output shafts.

 

[Diesel Nut]

I had Amsoil 75W-90 in my 93 dually front and rear.



I never changed out the fuild in my T case, but my Appplication Guide is saying to use ATF in the T case. I know all the newer trucks are using ATF in the T case.



You can check here -

Amsoil Application Guide

 

[Joseph Donnelly]

The 205 case in the first gens used 30 wt oil or 90 wt gear lube. I'd prefer the latter, or a multi weight gear lube in the t-case.

 

[Diesel Nut]

Duh! Your right, read the wrong t case. My mistake!

 

[btoscano]

Joseph Donnelly,



I think you meant 50 wt (not 30 wt) ?



Niki,



I am using 80w-140 synthetic in my axles year round. However, I live in the South and do a lot of long distance driving & some of its out west across the desert.



Brian

 

[1stgen4evr]

If you use heavier lube in any of the cases, the only negative result you will experience is a heavy shift for a few miles till the oil warms in the transmission. More important than anything is that you check each of them often enough to KNOW!!!! that you have ample lube and that of course means the extra qt in the Getrag. Pull the cover on the diff every 100k and look it over real good and use a pry bar to push things side to side and up and down. I have seen failures on the diff that were not at all associated with low lube which would have been discovered had there been some regular inspection.



I and my 500k mile getrag vote for heavier lube than motor oil. But I never roll empty. I deliver equipment and my list of 'just in case' is often more than 1000 pounds. Loaded I am closer to 20,000 gross.



James

 

[Niki]

If you use heavier lube in any of the cases, the only negative result you will experience is a heavy shift for a few miles till the oil warms in the transmission. More important than anything is that you check each of them often enough to KNOW!!!! that you have ample lube and that of course means the extra qt in the Getrag. Pull the cover on the diff every 100k and look it over real good and use a pry bar to push things side to side and up and down. I have seen failures on the diff that were not at all associated with low lube which would have been discovered had there been some regular inspection.



I and my 500k mile getrag vote for heavier lube than motor oil. But I never roll empty. I deliver equipment and my list of 'just in case' is often more than 1000 pounds. Loaded I am closer to 20,000 gross.



James

What do you run in your getrag? There is no way I'd put 5w30 in there, I have 10w40 now, was thinking of 20w50 synthetic or synthetic gearlube, 80w90 or whatever. I'm going to use 80W90 in my tcase and diffs not only because I have enough amsoil of that weight laying around from a previous project, but because it gets to 0 deg quite often in Chicago in the winter, and I don't want to change it before then. Maybe I'll put something in heavier next spring, who knows? Thanks for the tips guys.