This magazine advertisement is dated June 1966. I think the the advertising agency added a few Sunoco logos to the nose and right behind the drivers door to promote the Sunoco brand in this print advertisement. They do not appear in other photos from the Sebring race.
In the sixties you could fill a 20 gallon mid years gas tank with Sunoco 260 for less than $5. Gas was less than 25 cents a gallon. I always used it in my Vettes back then.