I have 125K miles on a 94 EX...i treated it with safoam and switched to 10w-30 mobil syntetic blend a while back, no leaks, now i wanna switch to full sythetic 5w-30, i am worried about leaks and junk, so if it DOES leak, can i switch back once synthetic has been in my engine...AND do i need to flush my motor with synthetic for thw switch?

Thanks