trans and tcase fluids?

[6.9poweredscout]

ok i filled the rears with 75-90 gl-5 synthetic gear oil. i was going to do the trans and t/c too as i bought a 5 gallon pail, but i was told it wasn't good for them. the rears are D60's one from a '85 GMC and the other a '92 dodge, the trans is a '86 ford t-19, and the t/c is a NP205 out of a '73 IH pickup.

someone suggested straight 50 motor oil in them, will that be good? and can i use synthetic?

thanks!
-Jon

 

[Black dawg]

75/90 is fine in that trans and t case.

 

[FordGuy100]

ATF in the transfer case. T-19 tranny can use a lot of different oils. I have Amsoil 15w40 synthetic motor oil in it, and it does perfectly fine.

 

[Black dawg]

ive seen atf in np205s several times with lots of miles and no probs, but they do call for gear lube

 

[82F100SWB]

That 75W90 will be just fine in your trans and transfer case, the old engine oil spec comes from the 70's, there was a change in the formulation of gear oil around 78 or so, and the spec changes from 50W to standard gear oil at that point.
But, those old cast iron gearboxes are none to picky as long as it's some sort of lube, GM speced ATF for it's late 205's(early 90's) Dodge did not, and there is no mechanical difference between a 205 speced for ATF and one that called for gear oil. Heck, the 93 Ford shop manual I have calls for 7 pints of ATF for a T18....

 

[opusd2]

Did an "expert" tell you not to use synthetics and just use straight 50 weight? It sounds like a contractor's kind of advice, lacking of any experience.

*Before I get any contractor's shooting back at me, I am just going by my experience as doing HVAC for 20 years professionally and having contractor's giving their expert advice that contradicted what worked after I repaired their advice ridden mistake. Nothing personal to anyone here...*

But also having done mechanical work on everything from tractors to mini-bikes since I was big enough to hold a torque wrench, I will advise that straight weights were once the rule of thumb and in some cases still are what you need, but in most cases synthetic transitional weights make excellent fluids. I am a firm believer in synthetics, and run them whenever possible.

 

[6.9poweredscout]

i always used 85-140 in my scout t-19's, in the EXTREME cold it'd be sluggish for a block or so. i assumed, especially synthetic, it'd be ok. it was some guys on the 'binder site i go on. the t-case is out of the early '70's.

thanks it'll save me some $$ as the pail was $120!
-Jon

 

[6 Nebraska IDIs]

Yea Jon just use the 75-90 that you already have. That will work just fine in those gear boxes.