hi there, well after some english problem to explain my problem i took my car to nissan shop, they are very good shop and honest about the price...well...they drain the tranny oil with a special machine form MOC, and they clear the transmission 3 times...put a new cleaner and trans. fluid.....the fluid was almost black...they told me that the nissan maximas, has to make the change of the full oil every 30,000 miles to avoid demage on the tranny...my car right now runs ok and smooth...so thanks a lot for all the help