What weight Oil for Engine and Diffs?

[renovate7]

I'm getting ready to change the engine and diff oil in my DUKW. The book calls for straight 30 in the engine and 90 weight in the diffs. Any harm or is it a good thing to use 15/40 engine oil and 85/140 in the differentials?

 

[NDT]

85W-90 in the gearboxes and axles. That is the modern equivalent of GO90.

 

[renovate7]

Thanks for the replies. I'm going to stay with 30 non-detergent in the engine and the 90 weight as the book calls for.

 

[Two Stroke Madness]

Non-detergent? That oil hasn't been used in engines since the thirties.

 

[CHIEFSONN]

Do you/we not need to use in the transfer case, differentials and and transmission a gear oil without sulfur for the yellow metals used in such items mentioned?

 

[renovate7]

The gear oil I'm using, from Wally World, says "protects against corrosion of copper and bronze bushings". It's GL5 rated. And I always thought you use non detergent for engines with no oil filter and detergent for engines with an oil filter. The detergent keeps the dirt
suspended so it can go thru the filter and be removed. If you don't have a filter you want to dirt to settle in the pan and not be continuously circulated in the engine. The filter on this 270 seems to be of minimal value as the lines to and from it are so small.

 

[clinto]

I had always thought detergent was for filtered engines, non detergent was for non filtered.

 

[CMPPhil]

Hi

To the question of Detergent or Non-Detergent Oil in WWII vintage engines. Many of them have oil filters and used from the start Non-Detergent. If you know that the engine has had Non-Detergent all along Do Not change to Detergent as it will likely start washing all the deposits out of the engine and in my experience the seals will start leaking oil.
I have 3 WWII CMP trucks all with oil filters and all had non-detergent oil. The 216 Stovebolt Six Chevy engines in the CMPs are very similar to the CCKW engine. My M5 generator, share the non detergent with a filter. One of the things I have seen with the filtered engines running non-detergine oil is that if the filters are changed with the oil the engines can be amazingly clean inside, no sludge at all.

When I rebuilt the engines changed over to detergent.
As most of us have seen engines which have not had the oil changed regurlarly it doesn't matter detergent or non-detergent they will likely filled with sludge.

Hope this adds something.

Cheers Phil

 

[CHIEFSONN]

What about the the oils using sulfur ? THat was my question.

Do you/we not need to use in the transfer case, differentials and and transmission a gear oil without sulfur for the yellow metals used in such items mentioned?