Regarding Jn. 5:18, Christ was not making himself equal to God by claiming the Divine One as his Father. Contrariwise, the context shows that Jesus' remarks were egregiously misinterpreted by those listening to him. Such confusion often happens in the Fourth Gospel. The Expositor's GT is correct about the reasoning of the Jews in John 5:
"The Jews found in hO PATHR MOU [Jn 5:17] and the implication in KAGW ERGAZOMAI a claim to some peculiar and exclusive (IDION) sonship on the part of Jesus; that He claimed to be Son of God not in the sense in which other men are, but in a sense which involved equality with God" (1:738).
While the Jews were justified inferring that Christ viewed himself as a/the unique Son of God, they were mistaken to assume that he was thereby claiming ontological equality with his Father:
"Since the discourse that follows [John 5:18] denies the 'Jewish' understanding of the equality of the Father and the Son, is the 'Jewish' charge that Jesus had broken the sabbath to be taken seriously? I suggest that in John's view the 'Jews' are wrong both in their understanding of the equality of the Father and the Son and of Jesus as a sabbath breaker."
See Herold Weiss, "The Sabbath in the Fourth Gospel," Journal of Biblical Literature, Vol. 110, No. 2. (Summer, 1991): 311-321.
Compare James F. McGrath, "A Rebellious Son? Hugo Odeberg and the Interpretation of John 5:18," New Testament Studies 44 (1998): 470-473.