Why my 2006 xterra oil gauge is all the way up on H? engine sounds good and it drive good....

there will be an oil pressure sender unit attached to an oil galley in the block
sound like it is that or ma bad connection for the wire

cold oil is thicker, higher rpm=more pressure .factory guage is actually working like it should. if worried hook external guage on oil galley plug and check oil press.manually.

sounds like a bad rod bearing. if auto trans put in drive hold brake firmly with left foot gently push on gas pedal with right foot if knocking increases with engine rpms bad rod bearing time for engine rebuild

The oil sensor sending unit is shot,

check your oil pressure sensor mounted on r/h side of engine behind the alternator. its a rounded lookin sensor with single connector. i would replace it.

Hi Kimberly,The dealer told you a lie,your year 2005 has problems with the oil pressure sending unit,here is a link on it and how to replace it. How to Replace Oil Pressure Sensor Sending Unit Here's another link to a new part. Duralast Oil Pressure Switch Here's another link to where it is and how to replace. Repair Guides Engine Mechanical Components Oil Pressure Sensor AutoZone com

the engine may be slugged up from lack of maintenance/oil changes, since the oil was black when you purchased the truck. was the light coming on before you changed the oil?? if not, try changing the oil filter for nissan one. if that doesnt do it than you can dump some internal engine cleaner into it if you want, but it may develop external oil leaks. the oil builds up a film after a while inside of you engine. if you wash it off, the engine may start leaking oil. to really diagnose this, you should take oil pressure reading at the oil pressure sending unit. you will ofcourse need some specialty tools to do this job such as pressure gauge and oil pressure sending unit socket to remove it so you can screw the gauge into it.good luck.

You're in luck
There is a possible recall on 2005-2008 nissan frontier/pathfinder and xterra, for erratic/inaccurate or
inoperative fuel gauge. This is the part# for the fuel gauge sending unit in question is #25060-ZS00A
Give your local nissan dealer and they should be able
to help you out. The reference number should be
#NTB07-069 AND 069A Hope this helps.

inner timing cover oil gallery gaskets are more than likely your problem...you can make your own for 10 dollars or give nissan 500 for a new cover as they dont supply the gaskets....check the oil pan for gasket material...thats a sure sign they blew out but they may be gone and still holding together so its not always accurate...

FUEL FITER , AIR CLEANER , OIL FUILD AND FITER , TRANS FITER AND FLUILD CHECK REAR END OIL AND BRAKES ALSO TIMING BELT WOULD BE VERY GOOD TO CHANGE OUT