t case oil??
 

this may sound stupid but i have heard a 205 take either ATF or gear lube

which is correct and what weight oil/atf should i use?

Re: t case oil??
 

you can use either one, I use 80/90 gear lube,I think it would be a little quieter than atf. synthetic would probably be great.

Re: t case oil??
 

From what I have seen, GM recommends gear oil for earlier years and then changes to ATF in later years for the same transfer case. Gear oil in mine.

Re: t case oil??
 

I've also heard either is OK, but I run gear oil... However, when the seal between the trans and t-case was leaking, ATF would be pumped into the t-case. When the trans needed topping off, it was time to drain the excess from the t-case. Having both oils in there never hurt it at all...

Re: t case oil??
 

I use gear oil in my np205.The only way mine will have atf in it is if the seal was letting it leak in..

Re: t case oil??
 

I guess I'm the only guy running ATF then, eh... Well the General recommends that you use ATF in the transfercases on all newer models, I consulted my dad who has been a mechanic for almost 30 years and he said to run the ATF, on the other hand I do have a 250 gallon tank of gear oil in the shop so I could've done either or.

Re: t case oil??
 

I run what ever is in the tranny. Auto tranny run ATF, NV4500 run syn, Manny tranny run gear oil. The 205 is a tough TC, she don't really care as long as it's plentiful and clean.

Re: t case oil??
 

Gear oil here!

Re: t case oil??
 

synthetic ATF in my NP208......230,000kms all original....going strong.

GM recommends dex III ATF in the NP208, so run it.....

Duro

Re: t case oil??
 

NP205's run 80w90 since it's an all gear t-case. You can use 85w140 also.

Re: t case oil??
 

yup, I am with the 80-90 gear oil crowd. I have the SM465/NP205 combo both filled with 80-90w :metal:

Re: t case oil??
 

Mine was running ATF, not by choice, seals let go:lol: Since my 205 has gears in it, I plan to run gear oil, heavier the better, JMHO

Re: t case oil??
 

Yea I agree 205 should be 80/90 gear oil. I got ATF fluid in my 208.

Re: t case oil??
 

Gear oil, recommended by dealer parts department.

Re: t case oil??
 

When I had my 1972 it called for 80/90 gear lube in the 205.
When I had my 1980 it called for 30w motor oil in the 205.
My 1988 V 30 calls for ATF in the 205.
They all work.

Re: t case oil??
 

I think it is due to tighter clearances in newer TC's and tranny's, that is why thinner fluids are used in them. If you tried putting 80/90 in your 1988 you would have a hard time shifting it.:uhmk:

Re: t case oil??
 

My 205 has ATF, when I redo my truck I am going to change tranny, currently it has a SM465 and I am going to swap in a NV4500 then I will run synthetic. alot of older truck from the north will have ATF in them, that way they could shift the TC easier when cold.

Re: t case oil??
 

My 1972 called for 80/90 gear oil in the case
My 1980 called for 30w motor oil in the case
My 1988 calls for ATF in the case.
They all work in a 205.

Re: t case oil??
 

Interesting resurrection...

Did these 72, 80, and 88 supposed callouts specify the TC? 72 is 205; 80 may be 203 or 205; 88 may be 205 or 208.

I think a 208 uses ATF and I don't know what a 203 wants.

So it seems to be more complicated than ATF is good for all...

Re: t case oil??
 

mine was filled with atf by the p/o i took the check plug out and it was 3qt over filled drained all of it and replaced with 80-90

Re: t case oil??
 

The info I posted is correct for a 205 transfercase.
There were no GM 203's in 1980.
My 1988 V30 has the factory 205. I bought these trucks new.

Pics are from my 1980 K and my 1988 V30 truck owner manuals. Nothing supposed here.

Re: t case oil??
 

That sure sounds like bad seals between the trans and the t-case... has it been OK since you put gear oil in?

Re: t case oil??
 

yes none so far they must have filled it up on a bench i dont know how they got that much in it :lol: