I'm putting in new flange because old was cemented into old tile floor and I put in new tile floor. I have drilled holes in cement to screw flange down,do I need to put anything into the hole for ultimate contact or will the 8 screws be ok? New I really need all 8?

The guy at HD told me how critical the drilling was, hence it has taken me 2 months to get the courage to drill the holes. My drain pipe is old cast iron, no room for cast iron flange so I bought the plastic one that fits into my pipe,I need to add the extension to get it higher (above the floor level). Do I screw both flanges down together, or put the second one on and just use the wax gasket screws to hold both together?

Also, I have read everyone is suggesting the stainless steel flange, didn't see this one at HD. Does the type matter that much? All advise is greatly appreciated

My suggestion would be to have a plumber install a new cast iron flange since your system is already cast iron. The flange will not need to be anchored to the concrete and pound-for-pound, you won't get a stronger or better setup.

with that type flange, the holes are critical.
i don't understand why you need spacers above the flange?
you can get a longer flange if the pipe is too low. just put spacers under each screw to raise the top of the flange so it is about 1/4 inch higher than the finish floor.
lastly, stainless ring is the best way to go.

m & m, good suggestion.. but, where will you find a plumber who can pack and pour a new flange?

I know some on this forum can do it.

i have a busy week ahead. not sure i can go from massachusetts to texas to do a small job.

Have tools. Will travel.