Hey I'm having trouble replying in the classified section, why?

Hey i saw a post of your about oil. I have a question for you, I just bought a Z today, NA 1995 with 96k no mods except JWT ECU and under-drive pully. seller used 15w-20 i have a bunch of mobil 1 Full Synthetic 10w-30. next time i do an oil change can i use 10w-30? will it harm anything?