This is from Wiki :-
"Widespread issues with engines consuming their own oil at abnormal rates, more significantly in the 2006 "RevUp" edition of the VQ35 engine. Nissan currently is replacing engines that are brought in and found to consume 1 or more litres per 1000 miles, but has not issued a recall as of October 2006."
Thanks for this. I think I'll give it a couple more K miles and see if it stabilises, if not then I'll bring it to the attention of the stealer.