I'm changing the oil in my t-case. The chiltons Book says 10w30 motor oil but all the Fords I ever owned I ran 80w90. My question is I will be plowing with this truck,is the 10w30 oil good enough?Should I or is it alright to change to gear oil?

 

I have always ran 80-90 in them.

I have drained atf out of them, they don't seem to mind.

 

Forgot to mention I already bought the XD Amsoil 10W30

 

In my opinion, i'd just go ahead and use the 10W-30 if it were me. I think it would make it shift easier in cold temps. I replaced a half quart of 10w30 with lucas trans or engine iol addative in mine last time i changed it.

 

I would never run anything that thin in a 205.

I run Lucas 80/90 in mine

 

I did the NV4500 conversion about 40,000 miles ago and had the transfer case rebuilt at the same time. I opted for using the expensive NV4500 oil in the transfer case to prevent any cross fluid contamination if the input shaft seal of the NP205 decided to fail. 90% of my driving is in the summertime here in sw PA and so far no signs of leaks, noise, and failures of any type to date.

 

I also use the NV4500 oil in mine, not necessarly by choice. I put a new seal in my transfer case but got the wrong one and my transmission oil pushes past it and fills the transfer case. My transfer case is about 2 quarts high now, but my transmission is no longer loosing oil.

 

I use 10-30 in mine, synthetic of course. I would think that it would be harder shifting into and out of 4x4, but then...how many times do you have to shift it in a day? (probably not many)

I have heard of others using the 80-90 weight without problems too. guess its up to you.

 

I believe the Dodge service manual suggested either 10W30 or gear oil could be used in those. However, every one I've ever seen came right from the factory filled with gear oil. Also I would think that 10W30 would be more prone to leaking than the thicker gear oil.

 

Something to consider, motor oil and gear oil viscosities are rated on two different scales. I don't have a comparison chart in front of me at the moment, but if memory serves, 10W-30 motor oil and 80W-90 gear oil are very close to the same viscosities. The only difference between the two is motor oil is intended for engines and contains additives and detergents and gear oil is just oil (most of the time anyway, if you buy the higher priced gear oils they often contain additives that will benefit axles and transfer cases). When used in a stock application (such as a transfer case in a truck), there is really no harm or benefit to using either one, although the gear oil is usually cheaper. If you choose to go with a higher priced natural or synthetic oil then I would recommend one made specifically for rear axles or manual transmissions.

 

Thanks for all the input guys.I think the 80 90 is the way to go ,atleast that seems right to me. I just didn't want to go against the manual without some other opinions.

 

Yea, should work fine. Thats all they used to use in them.

 

use gear oil. the weather where you live is the determining factor in what viscosity you need. its cold as sin here, I run 75 90 rp in my rebuilt tcase.

 

This is good info...Thanks!! I'm working on a NP205 conversion for the NV4500 in my crewcab and was thinking of leaving the inner seals out and just filling everything up with NV4500 fluid.