You should change your oil way more often than every 8 or 9 months... Im not sure what happens to synthetic oils when they sit for long periods of time wether they separate or not.

I have never had to add oil between changes and Im at 74000 now. Mine will "smoke" but its only water vapor never oil. With the cats and resonators on our cars you may never be able to tell its burning any. Are your tips staying clean like the insides if they get real black really quick that could be an indication.