When is the only time a new justice may be appointed?

The appointment and confirmation of Justices to the Supreme Court of the United States involves several steps set forth by the United States Constitution, which have been further refined and developed by decades of tradition. Candidates are nominated by the President of the United States and must face a series of hearings in which both the nominee and other witnesses make statements and answer questions before the Senate Judiciary Committee, which can vote to send the nomination to the full United States Senate.[1] Confirmation by the Senate allows the President to formally appoint the candidate to the court.[1] The Constitution does not set any qualifications for service as a Justice, thus the President may nominate any individual to serve on the Court.

Senate cloture rules historically required a two-thirds affirmative vote to advance nominations to a vote; this was changed to a three-fifths supermajority in 1975. In November 2013, the then-Democratic Senate majority eliminated the filibuster for executive branch nominees and judicial nominees except for Supreme Court nominees by invoking the so-called nuclear option. In April 2017, the Republican Senate majority applied the nuclear option to Supreme Court nominations as well,[2] enabling the nominations of Trump nominees Neil Gorsuch and Brett Kavanaugh to proceed to a vote

Hope this helps ;)

i believe it would be capitalism

oil! is what i am assuming