I like the John Deere grease, mine hasn't leaked since putting it in and it always steers easy. I had regular gun grease in one for years till it started to get stiff, when I pulled it apart, I seen all the grease was pushed out the top or off to the side, the teeth were dry as a bone.
Any 00 or 000 NGI grade grease will work, its just the corn head grease is what is available at most any John Deere dealer, plus its cheap.
http://lubromation.com/pdf/CONSISTENCYGRADES.pdf
