question on removing shower stem

I have a Eljer 2 handle shower body. The cold water faucet is leaking and I have to remove the stem to replace the washer. I borrowed some stem wrenches from a friend and of course he had every size except the one I needed. I believe the stem is 15/16" because 29/32" was too small and 31/32" was to big. I was going to try and borrow a regular deep 15/16" socket, but I noticed the stem has a 6 star configuration, while the socket is 12 star. Should I get a dedicated 15/16" stem wrench which is 6 star and not risk stripping the stem? Also is it possible the stem is metric? Happy 4th