best fluid for 203

[willymonster]

this may sound strange but what is the right fluid for the 203 i have found everything from atf ,90 weight ,motor oil in different cases which is it ? usually i toss these out so i have never found out but i am going to try one out for a while in one of my trucks

 

[tarussell]

NP spec'd out SAE 30 weight oil for the 203.

Tom

 

[willymonster]

oil

i did a search and found an artical for the part time kit and a new shaft they make to make sure it gets oiled correctly when swithed to part time they specified 40 weight . gotta admit i was really suprised to see that i always assumed they ran 90 weight. they even mentioned people running atf and 90 weight and said that was one of the main causes of premature failure

 

[tarussell]

I believe they want such light weight oil so that the small orfices (sp) can let the oil through to get to the 4 billion needle roller bearings used in a 203.
ATF is too thin and 90 weight is just too thick - SAE 40 weight should be fine for longevity assuming all else is well with the case.

A lot of shops/folks get confused as to what oil gets used in various cases since GM has spec'd ATF in all 208's and some 205's that had auto locking hub's while the rest of the 205's used 90 weight , but the 203's have always come with 30 weight oil.

Tom

 

[destinbeachman]

I have always used 20W50 in mine with good results and I ran it pretty hard even before I doubled it up.Couple trips from Florida to Memphis and once out to Utah and back.

 

[Cricket]

Both manuals I have Clymer & Haynes specify 10w/30 or 10w/40.

Anyone else have a different spec besides Tom's straight 30W. I know you know what your talking about Tom, just pointing out what these publications are recommending.

 

[tarussell]

Both manuals I have Clymer & Haynes specify 10w/30 or 10w/40.

Anyone else have a different spec besides Tom's straight 30W. I know you know what your talking about Tom, just pointing out what these publications are recommending.

It's all good ! Many manuals that I have seen over the years have stated several different weights but the one weight that seems most consistant has been the SAE 30 . I personally like the thickest oil possible and if I had a complete 203 that was not in artic temp's I would run 40 or 50 weight oil in it.

For those running a range box ( as in not the back half of the 203 ) I run regular 90 weight oil in it . I believe that the helical cut gears and radial bearings need such a heavy weight oil - it seems that the needle roller bearings that ride on the shaft get plenty of oil flow in the gear box portion of the 203.
Tom