RAD951

Whats this I hear that the mahle oil filters have a "backflow preventor" built in?? Do regular oil filters have that?? And whats the difference?? And does it matter???

Dave H.

OEM filters, Mahle and Mann, have an anti-drainback check valve inside to keep oil from draining back into the filter, keeping it up in the block and head. that's so oil is there when you crank the engine, you don't have to wait for the pump to get oil up into the mechanicals. think of it as instant oil pressure. non-OEM filters don't have the valve and are not recommended. Fram filters are the worst. they're not made to hold the system pressure that our cars have. many a watercooled vw has blown up a Fram filter.

don't know when porsche started using them, but vw's and audi's have used them *forever*...

IceShark

Well, the correct oil filter has a back flow deal that prevents oil from draining out as it is mounted in a stoopit position. I believe it is only a rubber flap, though.


So will leak a bit back down, still is a good idea. And for $5 on sale, just put this decision to bed, buy it and move on. How many oil filters do you know that are mounted screw inside down? That is why the backflow prevent is important.

icat

First off, I use the OEM filters and always have. Second off, why risk incurring the rath of the Porsche gods by using anything else - heck their only $5.

Now, having said that...

Since the filters are mounted "scew-side" down, why wouldn't a regular filter work just as well? If the purpose is to prevent oil from being trapped in the filter, then I'd think Porsche had solved this problem by mounting the filter "upside down". If you follow this logic, then a filter without the back flow preventer would actually work better on on our cars (944 and 951, not sure if 924 has same) as the oil would have a free path to re-enter the block.

Comments? <img src="confused.gif" border="0">

Schuey

I know the K&N has the same back-flow valve, etc. but is it THAT much better that the $5 OEM?

rfuerst

I believe the theory behind the anti-drainback valve is so the oil filter is all ways full of oil,so when you start the car the motor does not have to fill the filter before oil goes on its merry way to the engine parts.I believe the K+N filter has the anti-drainback valve,plus it has a nut welded on the end of the can to assist in removing a stubborn filter. <img src="graemlins/beerchug.gif" border="0" alt="[cheers]" />

Dan Gallagher

you guys were starting to scare me with all this talk about blowin up engines... i use a k&n filter

User 462021

Use anything but Fram.

Type_LT

I was forced to use a cheapo oil filter without the check vavle. After starting it would take about 3s for the oil gauge to raise. With the mahle filter it's up in an instant.

icat

[quote]Originally posted by rfuerst944s:
<strong>I believe the theory behind the anti-drainback valve is so the oil filter is all ways full of oil,so when you start the car the motor does not have to fill the filter before oil goes on its merry way to the engine parts.</strong><hr></blockquote>

Works for me! Thanks

RAD951

Thanks for the comments. I currently have a purolator one in my car. I guess on the next oil change, I will put a mahle oil filter.

Paul Bloomberg

Have any of you ever spent twenty bucks and then cut three of your most popular filters in half to see what the filters look like?
Some don't have hardly any filter material!!!!But I'm sure it is better material...YEAH : )
Every filter that I have seen at "Auto Zone,ect....has the little rubber flap at the bottom to hold the oil in.
Paul

Tremelune

The last two "OEM" filters I bought from my Porsche dealer (they changed the OEM filter) leaked. I switched back to Mahle. No leak. No prob.

PCinDC

Uh oh -
Used a Fram last time in my 84. About 50 miles ago. SHould I switch it out?


Paul

84 944
87 944

IceShark

For 5 bucks I would. Remember to top off the oil after the change.