Frankenbrew question

Joined
Apr 2, 2005
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298
Location
SC Coast
Need roughly 4 qts of 10-30 for a n205 transfer case

I have tons of 5w-20 and a bunch of 15w-40 laying around but don't have any 30w

Can I mix 2qts of 5-20 and 2 qts of 15-40 together and be close ?
 
If it's the NP205, that case was spec'd from ATF to 80W90, so mixing the two oils you have would work.

Personally, unless it's chain driven, I like to use gear oil. I use Supertech 80W90 in the Dana300 in one of my project vehicles.
 
I would be concerned with the ability of the thinner oils molecules to keep the moving parts apart with the high loads inside a transfer case. If it were mine I would not chance it. Oil is cheap, transfer cases are not.
 
Jim, are you referring to the protective film that EP gear lubes typically provide? If so, I agree.

I'm not sure gear driven T-cases operate without boundary lubrication (as opposed to any type of hydrodynamic action taking place - maybe under low loads?).
 
The US Army uses 15W40 in theirs (they like commonality of oil for the engine, transmission, and t-case) and it works fine.
 
Originally Posted by jdw1222
It is a chain drive.


If it's chain drive, then it's not a NP205. All NP205's are gear driven.

If it has a chain then it's a NP203 or NP208.

What vehicle is it in?
 
Originally Posted by Zaedock
Originally Posted by jdw1222
It is a chain drive.


If it's chain drive, then it's not a NP205. All NP205's are gear driven.

If it has a chain then it's a NP203 or NP208.

What vehicle is it in?


Originally Posted by Zaedock
Originally Posted by jdw1222
It is a chain drive.


If it's chain drive, then it's not a NP205. All NP205's are gear driven.

If it has a chain then it's a NP203 or NP208.

What vehicle is it in?



Good catch. 100% sure It is a np203. It's in a 74 f250. From what I have seen it is spec to run a 30 or 40w motor oil
 
Last edited:
I had one for 17 years … 15w40 Delvac and working good when sold to a ranch who took the plates off …
 
The spec back in the day was probably SAE30. Delvac 15W40 would be a good substitute and flow better when cold.

The 203 doesn't have a pump like other chain drive cases, so I wouldn't go too thick. Your Frankenbrew would be fine.
 
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