Re: Cheap filters....

[Mark Quinn/HNS <Mark_Quinn@notesgw.hns.com>]

Al Powell wrote a mini "treatise" on oil filters a couple days 
ago in response to my & other's enquiries on same.   Since then 
(this lunchtime actually) I went to my local Trak Auto and 
started peering into the innards of various brands of oil 
filters to see any differences.  While there I browsed through 
the applic guide for Bosch filters, and they had a section on 
the characteristics of their different filters which was quite 
interesting.  

One thing that Al missed was that, in addition to a filter 
having a bypass valve (or not), the pressure that the valve 
opens is important.  The Bosch filters supported a number of 
diff bypass pressure ranges (depending on type), the following 
being the most common: 8-11 (PS), 11-17, & 27-36.  Obviously, 
too low a bypass pressure would result in oil bypassing the 
filter medium when it shouldn't.  Just another data factor.

Well just another tidbit, according to the Bosch manual, the 
filter screw thread for Audis (most if not all, anyway) is 
3/4-16 (Std).  I wonder why it isn't metric?

-Mark Quinn