Agreed with above. If it sits for long periods, that could explain a lifter tick until oil pressure gets up to *****. I'd maybe try a good OEM filter and oil change as well. How often do you change oil?
I just got a 2008 lucerne from my in-laws with the 3.8L. They were crappy at best on maintenance, but it's free for the daughter. Has a lifter tick and they were going to junk it. I poured in 1/2 quart of ATF and let it idle for 20 min - quiet as a mouse. Had a little noise the next day - added another 1/2 quart and let the daughter drive it around the yard (yes we look like rednecks occasionally ). The car is now quiet on each startup and is due for an oil change. Just some pointers of what worked for me.