I don't know about fruit tree grease,but my late Uncle Joe got hold of some caustic gel used in the textile business.He smeared it along the top of his 2 metre fence.We were legless with laughter as a cat came into view.The bugger started lifting its paws in sequence going faster and faster until it had 4 paws in the air at one time .It disappeared from sight at this point. Uncle Joe called it "cat-on-the-moon".