Odd Oil Pressure readings with sub zero temps

[Rivman1243]

Since its turned fairly cold ( like 5 to 25 below zero ) my oil pressure has been really low (like almost nothing) until the engine gets to about 125 to 150* once it get there it starts to read normal. Normal readings for me are (air temp is at least 5 or higher) in the upper 2/3rds of the gauge when its first started then drops down as the oil and coolant get up to operating temp the reading is in the lower 1/3rd, then it will rise and fall with rpm changes.

The engine doesn't make any noises while this "low oil pressure reading" is happening. The oil level is on the full line when I checked it on a level surface after its been sitting for at least 5 min. Its 5w-30 Napa brand oil and a WIX oil filter. The oil has about 400 miles on it. When I start it cold if I remove the oil fill cap (while its running and showing low pressure) I can see oil splashing around the same as when its warmed up and the pressure is reading like it normally does.
I've haven't put a an actual oil pressure gauge in place of the sending unit yet so i don't know what the oil pressures actually are. I just ordered the adapter so I can put a gauge on and see what the pressure is.

So with all this info what do you guys think is going on? I know from searching here the sending units are not accurate. Is the sending unit crapping out? I feel like its probably ok to be driving but thought i would check in here.

Thanks

 

[86tuning]

try pre-warming the oil pressure sender before startup to help pinpoint the issue. a heat gun would do it quickly, but a hairdryer might do the job too. Or park inside.

since you can see oil spraying around, and there are no scary expensive noises, I'd guess the gauge is the problem. And more likely sender than gauge.

 

[4G63 POWER]

You probably used a really large filter. The larger the filter the lower the pressure.

 

[baldilocks]

Temps that low is where full synthetic becomes worth the money. It posesses superior subzero pumpability.

 

[bloc]

Oil may be splashing around but that doesn't mean it's operating at ideal pressures. The fact that the oil is so thick and sticking to everything may be avoiding the bad noises/damage. Keep in mind that the oil pump effectively has to draw all of that thick stuff up through the strainer and pickup tube using vacuum. For an example of what you are working with.. take a small amount of that 5w-30 and put it outside overnight then pour it into something else in the morning.

Visual example:

Agreed on synthetic.. the viscosity change for a given temperature is typically less than conventional oils. Not that you should dump yours.. maybe just makes the case for being more diligent about warmup times before driving hard. That, or an oil pan warmer/block heater/rad hose heater/etc.


Edit: Granted, we don't know the temperature, but this is for the guys claiming 15w-40 "works fine" for cold climates



Edit 2: extreme example, published by Mobil, but it shows the difference between synthetic and semi-synthetic in a given viscosity grade

Cold Weather Engine Protection For Your Car Engine