Winooski was laid down as Calusa on 23 April 1941 at Sparrows Point, Maryland, by the Bethlehem Steel Company under a Maritime Commission contract (MC hull 144); launched on 12 November 1941; sponsored by Mrs. Laurence B. Levi; taken over by the Navy on 5 January 1942.

She loaded fuel at Baton Rouge from 23 to 25 April and then set a course back to Norfolk in which port she arrived on the 29th.

After a nine-day availability at the Norfolk Navy Yard, the oiler resumed duty, starting out on a voyage to Deer Park, Texas, on 8 July.

In addition to her cargo of fuel oil, the ship deck-loaded two high-speed fire support boats for use in the invasion.

Winooski launched the fire support boats and, while they moved in to assist the troops assaulting the beaches, she proceeded to fuel the ships in the anchorage.

She continued fueling operations unmolested until 11 November when the enemy launched a series of submarine counterattacks against the invasion fleet.

At about 2000 hours that evening, a torpedo from German submarine U-173 struck the oiler just abaft of the bridge, punching a hole in her number 6 tank and damaging several other compartments as well.

After a brief yard period, during which four PT boats were deck-loaded on board her, Winooski departed Norfolk on 25 April for New York, there to join a convoy bound for the Mediterranean Sea.

The oiler brought every gun on board – including the light ma-chineguns on the deck-loaded PT's – to bear on the attackers but failed to score a kill.

The oiler remained in North Africa until 22 July, providing distant support for the invasion and occupation of Sicily.

She returned to Hampton Roads on the 20th, discharged her cargo at the Standard Oil dock, and entered the Norfolk Navy Yard for a 20-day availability.

On 5 December, she rendezvoused with another transatlantic convoy, this time off Cape Henry, Virginia, and set a course for North Africa.

The ship entered New York on 9 April and remained there until the 12th at which time she headed back to Texas for another load of oil.

The oiler arrived back in New York on 28 May and remained there until 8 June when she stood out to sea with another convoy, bound for Europe.

After a brief stop at Belfast Lough, Winooski departed for home on 24 June and reentered Norfolk on Independence Day 1944.

She remained in the Norfolk area until 14 July when she returned to sea with a convoy bound for the Mediterranean, a part of the force being sent to invade southern France.

On that day she departed Palermo and, after visits to Bizerte and Oran, got underway to return home on 4 September.

The oiler made a stop at Aruba to load oil and aviation gasoline and then set a course for the Panama Canal.

On 23 October, Winooski – by then a unit of the Pacific Fleet – embarked upon a long voyage to the Admiralty Islands.

She arrived in Seeadler Harbor at Manus on 16 November and remained there for more than a month fueling American warships and conducting underway training.

The unit with which Winooski steamed came under air attack several times; and, though the oiler herself escaped unscathed, one ship – USS Ommaney Bay (CVE-79) – fell victim to the kamikaze attacks and suffered such severe damage that American ships had to sink her with torpedoes.

There, the oiler loaded provisions, stores, and a cargo of fuel oil before getting underway for Zamboanga where she arrived on the 16th.

Two days later, she departed Zamboanga in company with TU 78.2.15 for the landing at Pollac harbor on southern Mindanao.

The oiler arrived at Tarakan on 2 May and remained there conducting fueling operations until the 7th at which time she headed back to the Philippines.

For the remaining three weeks of the war and through the first four months of the postwar period, Winooski steamed the length and breadth of the Philippine Archipelago delivering fuel to American ships throughout the area.

En route, however, she received a change in orders; and, after a brief stop in Pearl Harbor to disembark passengers and load cargo, she reversed course for Japan on 5 January 1946.

The oiler arrived at Yokosuka, Japan, on 17 January, discharged her cargo to ships at the naval base, and got underway for home again on the 24th.