Not my recipe, I saw it on a barbecue website.
I was a bit amused that on that forum, a couple folks didn't know what 'oleo' was. Then again, my daughters didn't know either when I recently asked them. I had to explain that in the 70s and earlier, oleo was a healthy(!) alternative to evil, artery clogging butter.
Related story: My mom told me that 70+ years ago (she's north of 90, BTW), it was illegal for food factories to color oleo/margarine yellow, lest customers would think it was actually butter. To bypass the law, the opaque white margarine would be sold in a sealed clear plastic pouch, and also within was a small tablet of yellow food coloring. A fun activity of my then preteen mom, was to bust open the yellow tablet and knead the margarine within the pouch til the yellow food coloring (gawd, I *hope* it was food coloring, now that I think about it!) would eventually change the oleo's color to a more palatable yellow color.