Xaos is correct... what you are seeing is not sap, it is very-rusty saltwater which is leaching back out of the iron/steel after decades of being submerged at an ocean beach. (This can also happen in freshwater locations.) For example, we civil war relic hunters very frequently see it happen on cast-iron artillery shell fragments we did on ocean beaches. If the frags are not properly cleaned and preservation-treated, they'll go to "weeping" very-rusty saltwater droplets, just like you are seeing.
The last time I saw something oozing out of an object that size was on a former bombing range in Arizona. The UXO guys came out and blew it in place. Good luck! View attachment 1946553
So nothing I can really do for it?