Hi Hung,
Long time mate
I would recommend that you change the fluids at 54,000 miles, same time as the spark plugs if they have not already been changed.
You are correct that Nissan do not stipulate a time or mileage for the fluids, however better safe than sorry.
I keep in stock the Genuine Nissan Fluids if you require them.
Denso Iridium plugs also in stock.
Click on my signature picture and you will find the plugs.
Drop me a pm if I can help you further mate.
Alex.