Omega Planet Ocean 2500D / to service or not?

I just picked up a Planet Ocean 2500D last week, in near mint shape. It is keeping amazing time at just 1/2 second fast per day so I'd rather not get it serviced if I don't need to.

My question is around water resistance. Since it is the 2500D movement, it was probably manufactured in 2011. I'm assuming it was never serviced.

I have no interest in diving with it but should I assume it has no water resistance or just less than it's full 600m?

Thanks!