Low oil pressure 3800 with ACDelco PF52E

[71Chevyguy]

Had something interesting happen recently. A while back I changed the oil in my LeSabre with the 3800. I put on an Ac Delco PF52E filter and filled it with G-oil 5w30. In the coming days I realized that the oil pressure wasn't quite as high as it usually is. The 3800 is famous for having high oil pressure at most times as long as all is well. Usually my oil pressure is 2-3 notches above 40 on the gauge while cruising and one notch above 40 at idle. Well at this point it was just above 40 when cruising and I had seen it dip down almost to the red at idle in traffic. Engine sounded fine though, silent as usual.

I hadn't gotten around to messing with it and since the car gets driven A LOT, the miles flew by quickly. So it is at around 5k on the oil and I decided to leave the oil (still looks about like light maple syrup after 5k) and just change the filter. I have some cheap $1 Rockauto filters that I picked up for short runs like after doing manifold gaskets etc since I have several 3800 cars. Well, I replaced the filter, took it for a ride and guess what? Oil pressure is back to normal! I have never personally had a bad oil filter, but it seems the filter was to blame. What could cause this?

I used the AcDelco this time but I had used several supertech (made in USA) previous to that and a bunch of Bosch before that. Never had any issues with the others. Now, had I not had an oil pressure gauge, I would never have known anything was any different. I will probably let the oil go another 2,500 miles, maybe use the other AcDelco filter I bought along with that one for the next oil change. Interested to see if both were bad in this case. I don't have an issue with the e-core design, it is similar to the cartridge filters I used for many years on my Ecotec I had before. But it seems this filter wasn't working right in some way.

 

[admzn]

I can't comment on what would cause it. But I have experienced a similar issue, with a Napa Gold (wix) filter. In my 95 Nissan, the oil pressure comes up fairly quick, as it should. But it would not with the Napa filter. I have an aftermarket gauge, but also noticed that the stock oil pressure lamp would stay on for a worryingly long time on startup. Swapped the filter out mid oil change for an [censored] and the problem went away. Napa gave me a new fiter for free when I went back.

Here's a guy with another similar experience on a acdelco filter:

https://www.youtube.com/watch?v=IGLr9NBFA1Q

Perhaps acdelco filters aren't what they used to be. I used to run them on my old grand am without issue years ago.

Edit: I find it hilarious that orange can of death is censored

I use them all the time.

 

[A_User55555]

When I had my old 1999 Deville, The dealer changed the oil and installed an AC Delco PF61E filter. A few thousand miles later, the oil pressure light would flicker at idle.

For the next oil changes I took it to an independent shop and gave them a PF61 Non-Ecore filter to use.

In the next 5 years until I got rid of the car, I never saw the oil light flicker again.

 

[Job]

At the sender, oil pressure of 40 and becomes 10 or whatever under the same engine speed and oil, means less flow at the sender point. That's the starting point to search for the reason. A new oil filter itself doesn't change flow. How would it do that?

 

[ZeeOSix]

Hard to imagine the oil flow being choked down from a slightly more restrictive filter with a positive displacement oil pump, unless the pump is going bad, or the pump's pressure relief valve is acting up.

If the oil pressure sensor was located before the filter, a more restrictive filter would make the pressure read higher.

 

[slacktide_bitog]

Filters for the 3800 don't have a bypass valve because it has a bypass in the block

Is that G-Oil the oil you usually use?

 

[71Chevyguy]

I have used all sorts of oils in this car. Most of the time I ran Quaker State Q-Horsepower in it, but trying to use up some of the older oils in my stash. The 3800 doesn't usually care what is in it as long as you change the oil once in a while and it isn't less than a 30wt. I don't think I have ever used straight g-oil in it because I know it tends to run a bit thin after a few miles. I usually mixed it with QSHM 10w40 at a 50/50 ratio. This engine does have a slight leak from the rear main seal so I do have to top it up once in a while. I did top it up with a quart of 15w40 Motorcraft to thicken it a bit, but adding the thicker oil didn't really help the pressure. It needed 1.5 qts added to get to 5k which isn't too bad for a 22 year old engine. This is why I replaced just the filter and left the oil, to see if it would change drastically and it did. This just seemed very odd to me.

 

[ZeeOSix]

Should cut the filter open to see if there's snything strange going on with the filter.

 

[71Chevyguy]

Originally Posted by ZeeOSix
Should cut the filter open to see if there's snything strange going on with the filter.


I may try to do that, just need to locate an exhaust cutter, I know I have one here somewhere, lol. If I do manage to cut it open, I will post pics of what I find.