Eaton has used 20 wt (Motor Oil) for a Long time... they recently, about 10 years ago approved multi-vis Synthetic Motor Oil... I have used both 20 and 30 wt in Eaton's And have switched them over to Mobil1 15W-50 ...
Don't use hydraulic oil in Eaton pumps...
Using motor oil, they are nearly indestructible...
Synthetic Motor oil is completely compatible with the oil in there... But I would drain out all that I could, (older oil will shear down)...
You could stay with a 20 wt Motor oil if you are using it in an area in colder temps... if it is primarily used in Hot summer use 30 wt... But you will be much better with the 15w-50 Synthetic Motor Oil...
:smile:KennyV
What plug are you referring to that may hold something together inside? I can't place it... Could you post a picture of it...:smile: