Willamette became the second ship complete the so-called "jumboization" on 27 September 1991.

The "jumboization" process consisted of five basic steps.

Between 1966 and 1968 Caloosahatchee, along with her sister ships Ashtabula and Canisteo, underwent "jumboization".

Upon completion of her 15th Western Pacific deployment on 14 October 1963, Navasota was scheduled for "jumboization", the first oiler so designated.

Upon returning to the United States on 23 July 1965, she prepared to enter the yards for an extensive "jumboization" conversion, with preliminary work conducted at Boston, Massachusetts.

In 1968, Ashtabula underwent a major reconfiguration, or Jumboization at Todd Shipyards, Los Angeles Division, San Pedro, California.

This jumboization was done by cutting the ships in two with cutting torches, then the aft section was pulled away, and new mid-body moved in and welded to the bows and sterns.

In December 1991, she completed an eleven-month "Jumboization" in the Avondale Shipyard, New Orleans, Louisiana, and returned to the Fleet as a greatly improved Fleet Oiler capable of delivering not only fuel, but also ammunition and supplies.