M hydraulic pump oil change

[Old farmall plowboy]

I am working on a 1946 M farmall it sat in the shed for 10 years changed all oil and filters it runs like a top. My question is I want to change the hydraulic pump oil in the belly. What kind of oil how much and where is the drain plug and oil level plug, Any info would be helpfull.
 

[Zachary Hoyt]

There is a drain on the bottom of the pump unit(this is assuming that you have the belly pump). There was once and may still be a dipstick inside the fill cap, which is on top. I know an H takes 6 quarts, not sure about the M. Hy-tran is what I used, it is a safe bet, or SAE 30 non-detergent if you want to be authentic.
Zach
 

[Old farmall plowboy]

Thanks for the information it is a belly pump. Dave
 

[Ellis Kinney]

I would definitely use 30 wt non detergent oil. My M will whine and not lift well with hi-tran but does perfectly with 30 wt. Ellis
 

[47M]

I would only use 30 wt if you're sure any implements you connect to your belly pump won't be used on any other tractors that use Hy-Tran. You don't want your 30 wt oil mixing with the Hy-Tran on the other tractors.

My M uses 6 qts in the belly pump. I use Hy-Tran and it works fine for me.