1946 D6 4R fluids.

I’m going to change all the fluids this weekend. What weight and type would yall recommend for the transmission and finals?

I’ve read a lot about not using a gl-4 or 5. Any recommendations on what’s good and cheap? I’ll take all the advice I can get.

I personally would use the 90 weight gear oil in the final drive I lives by where it stays above freezing most of the time. Transmission in my 1950s Cat gets 30 weight oil. I also use 10/40 weight good grade diesel oil in the engine. Not sure what the book says but I’ve had this machine almost 50 years with almost zero problems. Service pays off sir

I have always used 90 or 85-140 oils in the transmission, as well the finales.

The liter oil in transmissions did start until the 1960's. I did not get that message until the 1980's, then before I thought about changing found Cat had changed already again.

Ray, what does that tell you? It tells me both work. I’ll bet that thick stuff don’t work good in an extreme cold region. Be to thick I imagine.

Most likely. Anything slimy and slick, that does not foam.

A local that specialized in pickup and lite truck manual 4 and 5 speed transmissions, thought tractor hydraulic/transmission fluid was best gear lube in that application. Very thin compared to what I grew up with.

Not saying your answer was wrong, as I know Cat did go with the less types oil the less mistakes would be made. But also know they backed on some of it. Mostly in this old hobby iron anything wet and oily, is way better than empty.

Thankfully I don't live were it gets so cold. The lowest I have seen on my thermometer is 10F.