Unless it is an electric gauge and the amp draw makes the gauge thrown off. My alt was getting weak last summer and my sending unit was going out. Kick on the a/c and the gauge would start going up. It would do the same thing if you held the window lift buttons up.

 

Where you live you can use a 10w-40 easily.
It's not the water temp that matters so much as the oil temp, the hotter the oil the thinner it gets.
It gets to thin and it wont protect the engine parts and it will burn off more easily.

My personal preference for oil in the summer is Mobil 1 15w-50, with the summer heat and off roading with the family in the truck for 8 hours with the A/C on I like the added protection of the heavier oil, I also think it helps with city stop and go traffic.
In the winter time I use M1 5w-30 SUV.
This is my preference and you need to use the oil that is right for your driving conditions.

 

If you want to locate that noise, Carefully, 1 at a time, remove a plug wire while the engine is running. Chances are you will find the cylinder when the noise goes away when pulling that wire.
Ny the way, don't pull the wires with your fingers, you'll land up on your ***.
Let us know what you find.
Also thanks for the oil pressure numbers.

 

Yeah that happens too! if i press the windows down the oil gauge reading changes... it goes down...

 

Mike - if they noise goes away when pulling the plug, does that indicate the problem is somewhere in the valve train, pushrod, tappet area? I would think the noise would still be there regardless of whether or not the plug is firing. No?

My gauge is digital and does not seem to be affected by current draw from other uses. Josh, I'll email the .pdf to you. Your pictures were the reason I decided I could put something together myself. If my directions are useful to people, I'm hoping they can be uploaded/stored by the site somehow so people don't have to wait for me to send out emails.

 

If you have a noisey component for a cylinder, by pulling the wire, removing the spark, you take the load off of that cylinder, then at least you know where to focus when you are ready to tear into it for a repair.