Oil Pressure Change After Oil Change

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I had a little weird thing happen. I just changed the oil on the 80. Using the same Castrol GTX SAE 10W-30. Went from my last OEM big filter to the OEM small YZZD3 filter.

Now when I start up, the oil goes to the third tick mark of four tick marks (bottom, two marking thirds and the fourth the top) and it holds there until operating temperature is reached (a few miles). The gauge doesn't fluctuate with RPM at this time. Once everything gets warmed up it operates like always (second tick at idle and third tick at speed). In the past this didn't happen, it more-or-less just went to that third tick at start up and quickly lowered down to the second tick.

I know that this gauge is not accurate in any way, but this is sort of weird. I could put on a new filter or different filter or just let it be. Any thoughts?
 
Now when I start up, the oil goes to the third tick mark of four tick marks (bottom, two marking thirds and the fourth the top) and it holds there until operating temperature is reached (a few miles).
Sounds pretty much like mine with the YZZD3 and Mobil 1 10W-40 over the past several years. Oil pressure is always a bit higher with fresh oil, too.
 
This is perfectly normal and what should be happening with any car using any oil/filter combo upon start up when oil is cold and idle is up. The fact that what you are now seeing didn’t happen with the highly praised large filter is suspect.
 
Not the expert, but different filters (brands, sizes) have different specs for their internal bypass valves. It seems like what you may be seeing is on a cold engine the filter is bypassing (differently compared to the large filter) giving you higher pressure on start up, then as the oil warms up the bypass closes redirecting the oil flow through the filter media causing a drop in pressure.

If your oil pressure with the old large filter did not go as high it means
either the bypass valve didn't open or didn't open as much or as soon
as the new smaller filter, or the filter was more restrictive compared the new smaller filter IMHO. Something along those lines.


FWIW once I had left an aftermarket oil filter in too long (over a year, but vehicle was parked 3/4 of that time) that went bad. The oil pressure would suddenly and randomly shoot very high as I was driving down the road at a steady speed, then drop back down to the usual level. A new filter cured the issue.

For a few unfortunate people the opposite happened, their oil pressure dropped to nothing due to a catastrophic internal failure of the filter (WIX)
which damaged/destroyed their engine.
 
Sounds pretty much like mine with the YZZD3 and Mobil 1 10W-40 over the past several years. Oil pressure is always a bit higher with fresh oil, too.
Thanks!
This is perfectly normal and what should be happening with any car using any oil/filter combo upon start up when oil is cold and idle is up. The fact that what you are now seeing didn’t happen with the highly praised large filter is suspect.
The old big filter would do the high pressure thing but not for so long. The oil pressure gauge doesn’t start responding to RPM until the engine warms up now with the small filter. Not really worried, mostly curious now.
Not the expert, but different filters (brands, sizes) have different specs for their internal bypass valves. It seems like what you may be seeing is on a cold engine the filter is bypassing (differently compared to the large filter) giving you higher pressure on start up, then as the oil warms up the bypass closes redirecting the oil flow through the filter media causing a drop in pressure.

If your oil pressure with the old large filter did not go as high it means
either the bypass valve didn't open or didn't open as much or as soon
as the new smaller filter, or the filter was more restrictive compared the new smaller filter IMHO. Something along those lines.


FWIW once I had left an aftermarket oil filter in too long (over a year, but vehicle was parked 3/4 of that time) that went bad. The oil pressure would suddenly and randomly shoot very high as I was driving down the road at a steady speed, then drop back down to the usual level. A new filter cured the issue.

For a few unfortunate people the opposite happened, their oil pressure dropped to nothing due to a catastrophic internal failure of the filter (WIX)
which damaged/destroyed their engine.
Once the engine is warm it behaves like it always has. I’ve only driven about 40 miles.

I’ve never seen oil pressure gauge do this. It just sits at that third tick no matter the RPM or speed. Then as the engine warms up it gradually starts to drop and react to engine speed.
 
If the filter's internal bypass is fully open seems like that's what you'd expect.

You could change the filter and see what it does; which filter
brand/part number was in there and what's in there now?

 
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Interesting topic. I just changed my oil in 94 and using Mobil 1 M1-301A filter and 5/30 Valvoline Max Life as usual. That filter this year was physically smaller than the previous years - same part number and fit just smaller so something changed. But according to gauge my oil pressure running quite higher than previously too. I thought maybe my oil pressure sensor bad so replacing that.
 
Interesting topic. I just changed my oil in 94 and using Mobil 1 M1-301A filter and 5/30 Valvoline Max Life as usual. That filter this year was physically smaller than the previous years - same part number and fit just smaller so something changed. But according to gauge my oil pressure running quite higher than previously too. I thought maybe my oil pressure sensor bad so replacing that.
You could verify oil pressure using a test gauge before replacing the pressure sender unit. I’ll bet that they made the filter exterior smaller ,for whatever reason, but crammed the same amount of filter media into the smaller can.

I’m guessing that M1 filter has synthetic media of multiple layers that capture different size particles which allows a filter to hold more crud before is clogs and bypasses the oil. I suspect the smaller size of the filter is no compromise internally and probably makes removal and installation a bit easier.
 
If the filter's internal bypass is fully open seems like that's what you'd expect.

You could change the filter and see what it does; which filter
brand/part number was in there and what's in there now?
OEM small YZZD3 filter, bought at the dealership
 
OEM small YZZD3 filter, bought at the dealership
I read an article where a guy cut open several smaller size filters and the -yzzd3 was one of them. Turns out it’s a well made filter with about twice the media as others in its category. I am a bit of an oil and filter nut so I searched out a big filter that had good numbers on paper and ended up running a Baldwin B2 HPG for a while but after reading about the -yzzd3 I decided to start running it because it’s much cheaper and being smaller means it’s easier remove and install.
 
Thanks for the reminder to re-stock. Best 'cheap insurance' on the truck perhaps. 👍
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Seems to be behaving normally. I drove it all last week.
 

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