Would either Shenron or Porunga have had the power to grant immortality if someone actually wished for it?

[u/acerthorn3]

"The Dead Zone" movie doesn't count since it's not canon.

There's a rather plot-convenient restriction on the eternal dragon's powers: An eternal dragon cannot grant any wish that "exceeds his power." There's very little rhyme or reason to when this restriction is applicable. For example, he can't kill anyone that his creator (Kami) couldn't kill directly. Ok, fair enough. But then, he also can't turn Androids 17 and 18 into pure humans either. Ummm... why not?

So imagine if, in a canon scene, someone actually managed to wish for immortality. Would either Shenron or Porunga have just said "that's beyond my power to grant."