I just want to share the memo I got from our fleet management:

Below is a portion of the official statement of Nissan on the use of
synthetic oil on Nissan cars.


" ... it has been their policy that use of synthethic oil is not
> recommended for Nissan vehicles. The reason for which is some synthetic
> oil have higher acidity compared with conventional mineral based oil
which
> tends to wear out the engine gaskets and oil seals causing oil leak.
>
> Engine related problems caused by the use of synthetic oil will void the
> warranty."