Bud Mahoney shared a few of his special memories and offered this explanation to those questioning this ingredient on a recent Gathering Old Recipes Facebook posting.
"It's a type of "Margarine". "I'm so old, that I remember when it came, plain white. Looked just like Crisco. My Mom would buy it, in the late 1950's. It came with a small packet of "yellow" food coloring, so that if you wanted it to look like butter, you mixed the color in! Over the years, manufacturers began to add the color in the process. You can still buy "Oleo Margarine" at some stores; most of what you buy, that is not "real" butter, is a kind of margarine.