In some locales it is colloquially referred to as oleo, short for oleomargarine.
From the en.wikipedia.org
The rivalry between the dairy industry and the oleomargarine industry persists even today.
From the en.wikipedia.org
New York extended open palms to a long-haired oleomargarine heir who plans to give away his entire $25 million fortune.
From the time.com
We were the elite who used oleomargarine.
From the post-gazette.com
More examples
Margarine: a spread made chiefly from vegetable oils and used as a substitute for butter
Margarine (or), as a generic term, can indicate any of a wide range of butter substitutes. In many parts of the world, the market share of margarine and spreads has overtaken that of butter. ...
46. (1) Oleomargarine or margarine may be manufactured or sold in the Province of Newfoundland after the date of the Union and the Parliament of Canada shall not prohibit or restrict such manufacture or sale except at the request of the Legislature of the Province of Newfoundland, but nothing in ...