Pulled this excerpt from this page;
http://www.notre350z.com/forum/files/uploads/Anonymous/1319478639_pdf_article_109.pdf
How much is factual and how much is the usual Nissan scaremonger crap is anyone's guess.
I generally take anything stealerships have to say with a grain of salt (sometimes the whole salt shaker...)
I do however have a great relationship with my mechanic (who rebuilds all types of motors) and I trust his word over theirs ANY day of the week.
Quote below and link at top if you'd care to read the rest.....
Cheers
"Nissan service and owner’s manuals frequently say to use Nissan Genuine Coolant or the equivalent. What coolant is the equivalent? Well, it should have no silicates, borates, or amines, and the manufacturer of the coolant should be willing to state specifically it’s suitable for use in Nissan products (in writing).
Genuine Nissan Coolant is not expensive compared to other brands; you can be sure it’s safe to install, and it may impress your customers by using a Genuine Nissan product.
Nissan now makes two Genuine coolants available. The traditional ‘Green’ Long Life Coolant (LLC), which must be mixed 50/50 with distilled water, and a new longer-life ‘Blue’ coolant, which comes premixed. The new ‘Blue’ coolant is compatible and can be mixed with the traditional ‘Green’ coolant, but the resulting mixture will not have the ‘Blue’ coolant’s longer service life."