Its actually a B1500 3.9 v6 my question is on the oil guage its at about 30 when i start driving it go to about 100 but when i stop it go back to 30 is this normal

Bad pressure sending unit?

Never, ever disconnect an oil sensor. It does not lie. You have no oil pressure because your oil pump is not working or no oil in the engine.

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.

sun has nothing to do with it but heat may cooling system may not be working 100% hot days may over heat the oil and oil pressure drops,oil pump may be worn you need an accurate temp guage & oil pressure guage and monitor them next time it happens some engines have oil pressure watch dog that kills engine if oil pressure drops

Normal oil pressure at operating temperature should be around 40 lbs, 30 at an idle. Either you have a bad oil pressure sending unit or you actually have low oil pressure that indicates a serious engine problem.

find the oil preassure switch and install a tempeary mechanical guage and eye ball the oil preassure it sounds like low oil preassure

oil pump gears inside the lower engine, or electrical. 1st make sure its full on oil, then sheck it with another pressure guage to confirm its not actuall pressure.

First off I wouldnt drive your car until you make sure that you have indeed oil pressure and that the gauge is a false reading, driving your car if in fact it has no oil pressure will severly damage your engine, but firstly i would check the oil pressure switch its located on the passenger side of the engine right back from the oil filter make sure the connector is clean and free from oil and corrosion if the connector appears to be in good shape take a paper clip and insert it between the 2 terminals inside the connector your oil pressure gauge should peak at 80 PSI that tells you that your gauge and all related wiring are good and in working condition, secondly remove the oil pressure switch and hook an manual oil pressure gauge up to you engine and start the engine the guage should have a oil pressure reading anywhere from 30 PSI to 55PSI depending on engine temperature if theres oil pressure on your manual gauge replace the oil pressure switch with a new unit, if you still have 0 PSI on your gauge then stop your engine immediatly and start looking at your oil pump and lubricating system for a problem.

When the pressure reads low, are you hearing any knocking or tapping noises from the engine? If so, you may have worn engine bearings. I'd check the actual pressure by having a mechanical gauge installed on it in order to determine the actual pressure (your gauge is electro-mechanical and not quite as accurate) If pressure is actually that low the oil pan must be removed and bearings, oil screen etc need to be checked.
The reason pressure is always higher at first is that when cold the oil itself is thicker...as it gets hot and thins out pressure will drop somewhat, but should not go that low. Only other thing that can affect pressure in that way would be either a bad sending unit (you will know that after testing) or gasoline contamination in oil (happens if an injector is not working properly)
Good luck with it!

it sounds like your losing oil pressure you might want to get it checked dont believe the pressure guage on the dash they arent right all the time