BTW - I run 5w40 since I noticed oil pressure would drop when idling for some period of time during really hot days.

 

Yeah its oil flow that really matters, high oil pressure is kind of like high blood pressure, not always a good thing because it could mean there is a blockage in the flow or the oil is too thick to flow good.

 

Yep , I second that for sure , if you use "Thicker" (High Viscosity) oil then yes you will see higher pressure because there is more resistance to the flow of the oil which means you have less volume moving through your system !!!!!!!!!
You want volume - not so much all the pressure !!!!!
I will post this long but very informative Oil Link , read it , it will change the way you think about the weight oil you use and your longing to see pressure :

http://ferrarichat.com/forum/faq.php?faq=haas_articles#faq_motor_oil_basics

 

I replaced my sending unit for my oil pressure and I still do not have oil pressure reading on gage. Can someone tell me the approximate resistance the sending unit should be at idle or 1000, 2000 rpm. I grounded the sending unit wire and my gage climbs to max. I took a voltage reading from battery positive to sending unit and it read very close to battery voltage but after putting the wire back on the gage remains at 0. I have a decade box which will allow me to dial in any resistance from 0 to 1,000,000 ohms so I wanted to simulate a good sensor. I read about the same problem thoughout this site and I have a simple question have many people gotten what they found out to be bad "new" sending units from Toyota. I would really like to fix this with oem equipment.
If the wire is good from point a (gage) to point b (sending unit) and sending unit is good, gage is good, there is voltage to gage and the sending unit is definitely grounded (no teflon tape, and there is no restriction at the hole on the block and the oil is full and I have driven 3000 miles with no issues (so I must have oil, then someone please tell me what else to look for, PLEASE.
If I read the pressure with a gage screwed into the block then this should prove the sending unit is defective if all else is okay, right?

Thanks a lot!!

 

this is for eveyone that posts about oil pressure.

The guage on the dash is for reference to possibly alert you to potential problems.

If you suspect that there is a problem with your oil pressure then the only way to know for sure is to remove the oil pressure sender (or switch if you only have a light) and connect a good test guage and measure the actual oil pressure.

It is important to understand that there is a certain lack of precision and linearity designed into the factory guages and they are completely unreliable for diagnosis.

 

Yeah , thats why in the previous post I recommended to use a separate meter with adapters for the 1/16 oil line to gauge , that is what I call a analog oil meter .

Your not going to have voltage on that line when you hook it up since generally all those sending units do is close or make a resistive link to ground .

If you can find a way to adapt the sending unit hole to a common thread then you could use a 50psi gauge of any type , if it were me I would try to adapt it to 1/4" (A/C fitting) and use my refrigeration gauges or 1/8" and screw a cheap 50 psi gauge in it and fire it up .

May be that you do not have any oil pressure so to rule the gauge out you will have to have another totally diff. source/gauge to verify , but that is better than throwing a rod through the block possibly