Here's what the manual states, see below. I have heard some use corn head grease others use an 80/20% combo of axle grease and 90Wt. filled about 3/4 full.
you should be able to find corn head grease at your local CIH dealer if they have combines. i will be gone for couple of days, but if you dont find, PM me your city & i will go on DRL locator w/the part # and find it for you when back to work. i know last fall it was B/Oed, but i believe we did get some in since.