Cheap filters....

["Al Powell" <APOWELL@agcom.tamu.edu>]

tgsgronback@mindspring.com (Steve Gronback) asked:

>         I purchased a Fram oil filter for my '91 20v 200 Quattro Turbo.  It
> fits, is cheap, and is the correct Fram part #.  The dealer, however, says
> don't use anything but the Audi filter (at 10 times the price).
>         Is this good advice?  Is the Audi filter gold plated.  Does it matter?

IMHO, if you buy a cheaper oil filter, that's what you get - a cheap 
oil filter.  Cut a Fram apart with a hacksaw (what's $1.98 
anyway...) and you will find that it's a shell with a thin piece of 
filterboard inside.  Worth less than it cost you.

And Mark Quinn/HNS <Mark_Quinn@notesgw.hns.com> asked

> Last week I posted a question about where to get Oil Filters
> for the A4 (cheaper than the $20 my dealer wants).  I got a
> couple responses including someone suggesting using the Diesel
> engine filter.  That got me to thinking ... what is the 
> difference between ANY oil filter?  I had always assumed that
> the fitting (size) was the thing, but looking around an Auto
> parts store over the weekend, many (not all) filters use the
> same screw dia/thread/seal dia and only differ by outside
> dimensions of the can itself.  Assuming the same screw/seal
> fitting and that the 'can' will fit and is as big (or bigger) 
> than the original, is there other difference between filters 
> by a given manufacturer (PLEASE leave manufacturer to 
> manufacturer differences out of this thread!).

Off the top of my head, differences include the following:

a)  Inside thread
b)  Outside diamater
c)  Total capacity (1/2 qt. vs. 1 qt. vs other)
d)  Anti-drainback valve, or not?
e)  Bypass valve, or not?
f)   Quality of filtration material.
g)  How well the filter gasket is supported.

FAIR WARNING:  I have strong perferences in oil filters and 
lubricants, often voiced on this group.  I think the Amsoil filters 
are the best for the money, and I will use their qualities to illustrate 
this response.

A and B are not material.  They just fit.

C is material if a manufatturer makes two filters which fit your car, 
but one holds twice the oil of the other.  You are better off using 
the larger one, if it will fit.  Why?  Because you run more total 
oil, which adds to your engine cooling (oil is a big-time heat sink) 
and because more total filtration surface means you will filter more 
of the oil circulating.  Both are GOOD.  

D and E are both desirable.  Filters which have one or both valves 
are better than those which do not.  IF your filter mounts pointing 
straight down, the anti-drainback filter doesn't matter much, as 
gravity will not drain the oil out.  If it mounts horizontally, then 
an anti-drainback valve keeps you from having to pump up pressure in 
the filter every time you start after the car has sat for a while.    
I will note that all Amsoil filters have both kinds of valves.  Most 
(I would suspect all, but I've never looked....) Frams have neither.

F is very important.  Most of the filters out there use one layer of 
filter paper wrapped around a center post, and they are flimsy, to be 
extremely kind.  Buy a Fram and Purolater and whatever else you want 
to, cut the end off, and look at the innards.  Highly educational.  
Amsoil filters use over 1/2" of dense filtration material from top to 
bottom in the filter, and they filter particles down to only a few 
microns in size.  They are heads and shoulders above the others I 
have inspected.  I'm NOT saying there aren't filters which are as 
good, just that I have never found them.  It would be nice if someone 
on this group would take a hacksaw to one of the Audi filters and 
report their findings.

G is important!  The first thing my Chevy pickup did after I put on a 
cheap (aka: Fram) filter was to blow the gasket right out the side of 
its mount.  Trust me, it WAS properly installed and tested - but 1/4 
mile down the road, POW!!!!  I looked and there was an oil slick down 
the center of the road.  There really wasn't much to hold the gasket 
in place on that Fram.  I replaced it and have had no problems since.

> Well, am I going to stir anything up here?  I really am 
> interested if there are any diffs in filters other than 
> fitting & size (& manufacturer!).

Mark, that oughta be stirring up enuf fer' today!!

(But that's OK, the other list-members knew I would do this....)  ;-)



.......................................................
Al Powell, Ph.D.                 Voice:  409/845-2807
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