stoker-man wrote:If your gear box is large, blue, and has a 90 degree elbow to fill it, it uses the light oil. Fill so you can see the oil in the fill elbow.
Note all AP-520 use the large Reducing gear box with the 90 degree elbow and some of the early DF units had them
aswell. Also some had a small glass window in them so you could see the oil level