Manning

The guy who did the filter study reported that the STP filter is made by Champion Labs (not the same as the sparkplug company). They seem to make a ton of different branded filters, so it would be no surprise that the "Porsche" branded filters marked Made in the USA are actually Champion Labs filters.

http://minimopar.knizefamily.net/oilfilterstudy.html

Click the link at the top of the filter study page for German Filters to see reports on Mann and Mahle filters. He seems to think they look pretty good, though I am still underwhelmed by the Mahle filters.

Slow oil pressure build caused by an oil filter means leaky anti-drainback valve. The anti-drainback valve in the Mahle filters may have a nice rubber seal and beefy spring, but that doesn't mean they seal properly after being heat cycled. My experience with the Canton Mecca filters showed that the rubber seal worked well for the first couple hundred mile. However, after being flexed open with hot oil flowing over it while the engine was running the seal would take a set and leak, allowing the oil to drain back. Again, maybe the two Mahle filters I used were just bad and it was a fluke that I got them, but I suspect that the same thing was happening to them.

Also, since the slow pressure build problem goes away completely when I use a different brand filter I think I can safely rule out other issue such as cracked pickup tube, bad pressure relief valve or bad oil pressure sender.

951Tom

Manning, that's an interesting topic about the seals going bad after heat cycling. The rubber stills seems soft and pliable after 3K miles on my 951.

I cut the media in half and was surprised....the large spring actually pushes the filter media to the base & seals it. The bypass valve is actually on the opposite end of the check valve and only visible once the filter is cut in half. It has a very stiff spring too. The bypass gasket is the end with the smaller round black circle. I'll post some more pics in awhile.

Manning

Yeah, the rubber seal in the Canton Mecca filter is still soft after being heat cycled, but it has definitely taken a set (is distorted) and no longer seals. This occurred on every single one of the CM seals I replaced.

951Tom

Here's a pic of the internal parts laid out in order (except for the bypass valve). The metal piece sticking out the side is the crimped piece used to hold the media ends together. I cut out a portion of the filter media and stretched it out flat to about 77 inches long. So the filter area is roughly 288 sq. inches. I'd like to cut open the STP and compare this measurement so if anyone with a STP wants to do this, please post. I'll cut open the Purolator at the next oil change if someone reminds me. Again this is my first "analysis" so feel free to comment.


Now here's one thing I noticed that might be worth mentioning that I think the big website does too. This is the bypass valve cut & pryed open. A rubber disc is pressed over the hole by the strong spring. If this disc were to somehow come dislodged and make it's way out from underneath the bypass valve housing, it could impede oil flow at the check valve and result in a pressure drop. I noticed the check valve has little tabs to hold it's sealing disc in place. I think the only way for the disc to make it past the check valve, would be if the rubber disc broke into small chunks which by then would probably be your fault for not changing the filter ever. The disc was still in perfect shape, sealed good, and there was no indication a problem was occuring. The bypass valve definitely seems to seal well based on the spring pressure felt by hand and should prevent any oil flow past it until the filter media is 100% restricted.


Here's a pic looking at the bypass valve before I cut it open.


Here's a pic of the check valve disassembled and the hole leading out of the filter can now be seen. You can see the little tabs holding the rubber disc in place here. This spring has very light pressure but should still seal fine and easily open once pressure is reached.

jd944

After using Purolator filters on my 84 for about ten years, I tried an STP filter at my last oil change because I couldn't get a Purolator. I see no difference at all. The price is great and they are usually stocked at Autozone. The oil filter report that has been mentioned is pretty good reading. They do rate Champion and Purolator products highly. The bottom line is stay away from anything that is made by Fram. I'm a member of another forum that deals in old big block Fords and just recently, a couple of members who were big Fram supporters reported oil filter related problems/failures. Issues like torn filter media and fluctuating oil pressure.

Tony K

Try using a MANN filter.

M758

Manning,
Your slow oil pressure build up...

What is this?

When you start the car does it take some time for the oil pressure to build up? Does it slowly build up in 2-3 seconds or does it have zero pressure adn then snap up?

My spec car running AMSOIL 20w50 Racing and a Mahle filter had the following issue.

Oil pressure would take at first 1-2 seconds after start to reach max on stock gauge. Then after a couple track sessions it would slowly go up in about 2-4 seconds. Now the pressure says at zero for 10-15 seconds. Then snaps to 5bar and the car runs fine after that. I was assuming the issue was with my oil pressure releif valve (old 3 piece style), but could the oil filter be causing this problem?

951Tom

M758, I'd hook up a external mechanical oil pressure gauge and start the car. This will tell you for sure if it's the sender or not.

M758

It is NOT the sender. That I am 100% Sure of.

The_Phantom

I like how the K&N filters can be removed with a 1" socket which seems to be a much better way to remove a filter than using an oil filter removal tool.

Manning

Joe,

When I ran either the Canton Mecca or the Mahle after the anti drainback valve started to leak I would notice a valve train noise when I would start the car, which would go away a few seconds later after oil pressure built up. When I watched the gauge I would see no pressure, then it would bump up to about 2 or 3 and build from there.

On the other hand, while using Mobil 1 or Purolator filters I get pressure build immediately.

Tom,

What are you referring to when you say check valve and bypass valve? Which one of these do the rest of us call the anti-drainback valve? The bypass valve is designed to allow oil to "bypass" the filter media should that media get too clogged right? And what you are calling the check valve is the anti-drainback valve which should actually be at the base of the filter and prevents the oil in the filter from draining back out though the many holes around the circumference of the filter (inlet holes), right?

Manning

This is part of the anti-drainback valve, right?

951Tom

Yes, sorry for the confusion Manning. By check valve, I mean anti-drain back valve...to keep oil in the filter after shut-down. You could say the Mahle has 2 anti-drain valves. The one pictured below holds oil on the clean side of the filter. If this valve leaked, only filtered oil would run back to the motor.


The pic below is the bypass valve disassembled. I think it can also open on start-up pressure spikes but normally it stays closed so all oil goes thru the filter.



And the pic below is the input side of the bypass valve on the filter end cap.

951Tom

There is a anti-drain back valve in the cyl. head....maybe yours is bad and is causing the delay in pressure.

Manning

I'd say that might be the case if other brands of filters didn't completely eliminate the problem. And if the problem didn't start a couple hundred miles after installing the Mahle filters.