Oil Pressure Changes after OC

[Jim Allen]

Here's an FYI relative to this earlier discussion: Logic Check in the form of a before and after snapshot of the oil pressure before and after an oil change on the following vehicle.

Vehicle: '05 F-150HD 4x4, 5.4L 3V, 19K total miles

Conditions: 80 ambient temp, truck driven over same route to approximately the same stabilized oil temp and the pressures were recorded at the same points along the way

Lubricant: RP 5W20 API-SL

Oil Filters: Old filter was MC 820S, new Royal Purple 20-820

OCI: 7463 miles


Old/New

Oil Temp: 195F/197F
Coolant Temp:195/195
Idle PSI(600rpm in gear): 26/26
1788 rpm (steady cruise @ 55 mph, level): 61/63

Conclusion: No notable changes. Will be sending in oil samples to see if there were any changes in actual viscosity, and to see how the RP held up generally after 14.5 months and 7500 miles.

 

[JohnBrowning]

Why would you expect a change? What was in it before? Does the oil pressure guage read live or does it pull from the computer? Few show actualy oil pressure and even then they have a heavy dapening ratio so you guage is not bouncing around like mad. I know their are brands that do not read actualy pressure they just read some predetermined value after start up and stay with that value unless their is a sudden drop or increase. So the OEM oil pressure guage might not be the ideal tool.

A lot of companies have made their oil pressure guage a modified idiot light because too many people complained about fluc. oil presure,amperage,volts water temp etc.....

 

[Jim Allen]

Hi John: I mentioned in he previous post (referenced) that I had installed new aftermarket gauges. In fact, these are Isspro stepper-motor gauges, generally acknowledged to be the among the most accurate types. They are not dampened.

Many people report oil pressure changes after oil changes, the theory being that the change is from the oil viscosity changes. The basic question was whether the usual drop in viscosity would show up on an oil pressure gauge. Until I know if, or how much, the actual viscosity changed on the 5W20 oil, I won't know how to correlate anything, but there wasn't much change on the gauge in this case. I just thought I post the early results... non-spectacular as they are. When the UOA/VOAs come back, I'll post them too.

Down the road, I will likely try a 5W30 grade (maybe even a 10W30) to see what effect that has on oil pressure and VVT operation. I will datalog a snapshot of the VVT operation with fresh 5W20, then try it again with a 30 grade.

 

[Zaedock]

Originally Posted By: Jim Allen
Down the road, I will likely try a 5W30 grade (maybe even a 10W30) to see what effect that has on oil pressure and VVT operation. I will datalog a snapshot of the VVT operation with fresh 5W20, then try it again with a 30 grade.


Jim, I have an '03 with the 5.4L. I'm running Q-Torquepower 10W30 have not seen a change in oil pressure. In fact, I haven't seen a change going back and forth from 5W20, 5W30, or 10W30. It's probably a dummy based gauge though.

Your results will be interesting with your accurate gauges.

 

[Jim Allen]

Your engine is a non-VVT, 2-valve, if I'm not mistaken. That would take any potential for VVT problems out of the equation (not that a 30 grade is reported to be much of a problem with VVT anyway) but it's interesting to note that you don't see any changes between 5W20 and a 30 grade. My OE gauge didn't move an millimeter.