Re: If it's so important...

[steveb@falcon.kla.com (Steven Buchholz)]

> 
>  "If the oil filter is mounted perfectly upside down (hole Up)
>    and the media is indeed "trapping" particulates, is the
>               check valve found in some filters still very useful?"
> 
... I don't think that the purpose of the check valve is to prevent 
backflow of trapped particulates;  I thought it was a way to keep the 
oil from draining back into the pan from the galleries through the 
filter.  If you think about it, assuming that there is backflow through 
the filter without the check valve, even a filter oriented vertically 
could possibly discharge contaminants back into the oil pan when the 
engine is shut off.  

HTH!
Steve Buchholz
s_buchho@kla.com
San Jose, CA (USA)