CITIES SERVICE TANKERS CORPORATION.

The earlier flag places a smaller black-and-white emblem within a broad annular frame. CITIES SERVICE OIL runs across the upper arc, with the motto ONCE, ALWAYS in a black-outlined oblong at the base. Merchant Ships 1949 calls the flag unknown, and Jordan does not define the funnel emblem.

C562 instead reads CITIES SERVICE OILS and ONCE ALWAYS, in black. The dexter side of the delta triangle is narrower, possibly a printing difference; Loughran shows the same difference in C563.

Loughran dates adoption of C563 to the late 1950s, assigning its funnel to ordinary tankers and C564 to super-tankers. Brown 1958 gives C563 a narrowish black top. Mitchell records C563 for Grand Bassa Tankers, together with its own version of the later design, identified in the source as G212.

The new flag adopted in 1974 is green with a triangle in three shades of red, edged white, above white CITGO lettering. Mitchell shows black letters on a white panel on the corresponding funnel.