Many older corn heads require special “corn head grease” to lubricate the row unit gearboxes. Customers have asked if they can use standard grease in those gearboxes to avoid having to switch grease cartridges in their grease gun.
Corn head grease is National Lubricating Grease Institute (NLGI) Grade 0 grease. Standard multi-purpose agricultural grease used to lubricate bearings is NLGI Grade 2. Grade 0 corn head grease is near-liquid when warm. Corn head row unit gearcases are oddly shaped and benefit from having a semi-liquid lubricant that can flow into all their nooks and crannies, as well as being easily flung around the interior of the gearcase by spinning gears.
One of the functions of grease is to cool gearcases. The lube gains heat from contact with gears and bearings, gets flung to the sidewall of the gearcase and transfers that heat to the sidewall as it drips/slides into the sump. If a lubricant is too thick the gears just carve a pocket in the grease and there’s no circulation to transfer heat. If the lube is too thin, there is risk of inadequate lubrication of the faces of the gear teeth, and the gearcase might overheat if the grease runs off the walls too fast to fully transfer heat.
So, yes, it’s possible to use standard multipurpose grease in corn head gearcases, but for maximum mechanical longevity it’s not recommended.
To confuse the issue even more, many newer corn head gearcases now use 80w-90 gear oil instead of corn head grease. All I can say is the bearings and seals in greaseable gearcases prefer corn head grease, and the bearings and seals in gear oil gearcases were designed for the more liquid lubricant.
