So I have a 93 touring which I changed the oil and oil filter on recently. I noticed after changing everything the oil pressure seemed to have dropped drastically. This is using a Defi oil pressure gauge to get the readings from as well.

Before the oil change at cold start used to go up to 95-ish PSI then drop down to 26-28 psi at warm idle. It would also have 65-ish PSI at 3k rpms when at full operating temps.

After the oil change cold start is at 60 psi and then drops down to 10-15 psi when warm, and will only get to 35-40 psi at 3k when at full operating temps.

This has been with 2 different filters as well: WIX 51635 and an NPN L146122 (bought from Rotary Performance directly). I've attempted to search online in general for simliar issues regarding oil filters and oil pressure, but get "faulty filters" as a result. If you search via rotary you get a TON of pages stating "replace the oil sending unit" which I'm not using already anyways due to the defi oil pressure gauge.

Order of testing this was WIX filter (low oil pressure), and put the old filter back on (TVI V 4162). Then there was pressure again, and then bought the NPN. Realized it was doing the exact same thing... and put the old filter back on again and I have good pressure again. Any thoughts? Anyone else experience this? I am going to stop by a mazda dealership and get a legit OEM one to try as well.

 

That's just weird. I've always run Purolator oil filters, they are easily available and do great. I get the PL14459 filter, it's the Purolator Pure One filter for the FC. It's bigger than the FD filter and has more surface area but does require more gymnastics to get to.

Dale

 

yes this definitely has me scratching my head.

 

Specifics of oil brand and weight used?

 

^Not sure about oil brand, but agree....what viscosity was used before, and after?

 

Edit,nvm

 

You can choose filtering or higher oil pressure.

That TVI filter probably had the filter media become unglued so oil is bypassing the filter.

 

So never had this problem on the FD but with my Audi, I ran a knock off filter once and it indeed caused low oil pressure. So much so that the flashing oil pressure warning light came on. I checked the oil level and it was fine. Changed back to an oem filter and bingo... it went away. Filters do make a difference in my opinion.

 

the skyaktiv/MSPII engines are like this too, you MUST use the Mazda filter. the oil pressure is managed, and if you use a different filter it can't/won't react fast enough, and the bypass will be open.

 

Oil filters are indeed weird. Replaced an engine in an 06 volvo s40 and got the filter from autozone and it would tap at startup. Was told the oem at the dealer would fix it and it did. Crazy thing was they looked exactly the same visual wise...

 

So i had found some more time to mess with this a bit, and I'm pretty sure the old filter was just "bad" or something. I'm surprised it didn't mess anything up engine wise... or it might have I'm not sure just yet. After learning more about how the oil system flows throughout the 13b-rew The pressure sensor was before the oil filter... I've tried 3 different brand filters, and discovered it did the same thing on all 3 different brands. One of them was even from Rotary Performance that they use on a lot of their engines, and they have had 0 problems with the filters themselves. So I started going "downstream" to find out why there isn't pressure. I have replaced the "pellet" with the atkins piece, and that seemed to kind of help, but it still sucks with the amount of pressure. Looks like the next things are either really difficult to get to, or internally in the engine. I have decided to put this on the back burner for now until I get my house situation that has came up figured out. Basically going to just rebuild it at this point as preventative maintenance, and one of those "while I'm in there" types of things.

 

Just curious, if this a unit with sender, why not install an inexpensive mechanical gauge just to test?

 

I actually took the autometer gauge out of my corolla and installed it, and it was reading the same as the defi gauge was.