Once upon a time, many, many moons ago, they made a grease gun with a special tip for those cast fittings. Actually, two or three types. Best one had a rubber insert in the tip that simply pressed against the fitting. There was a similar one that instead of the rubber , simply had rounded/concave end that likewise pressed against the fitting. Those types were hand-packed with grease to fill. Those were an easy after-the sale-accessory item along with a can of grease when closing the deal on a new motor. Then there was the one that had a similar tip and screwed to the end of a tube of grease. That one was nice, but didn’t work well.
I’ll look when I go out to the shop to see if I still have a gun with one those tips and report back if I do. The one with the concave end would be an easy one to reproduce.
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