Date: Sun, 4 Dec 2011 13:14:14 -0600
Reply-To: Tom Hargrave <thargrav@HIWAAY.NET>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Tom Hargrave <thargrav@HIWAAY.NET>
Subject: Re: Oil recommendations simplified
In-Reply-To: <4EDBBDA8.4050802@gmail.com>
Content-Type: text/plain; charset="us-ascii"
There is a fundamental difference between oil bath and a K&N air filter & a
oil bath is probably the best filter made to date.
A oil bath air filter works on a principal of physics - that a mass in
motion wants to continue in the same motion. With a oil bath filter, the air
is driven straight down towards the oil, then the air does a abrupt 180
degree turn back up before being sucked through the mesh part of the filter.
The dirt, even the small particles, continue down and into the oil because
dirt has a lot more relative mass and can't make the turn fast enough. The
light fluffy stuff that is carried around the 180 degree turn is caught by
the mesh filter.
The K&N is not a oil bath air filter - it does not work this way.
Thanks, Tom Hargrave
www.stir-plate.com
www.towercooler.com
www.kegkits.com
-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@GERRY.VANAGON.COM] On Behalf Of
Michael Snow
Sent: Sunday, December 04, 2011 12:36 PM
To: vanagon@GERRY.VANAGON.COM
Subject: Re: Oil recommendations simplified
On 12/04/2011 01:00 PM, Robert Stevens wrote:
> On Dec 4, 2011, at 10:26 AM, Tom Hargrave wrote:
>
>> I knew right away what had changed - I installed K&N air filters and
>> yes they were oiled, they came with oil in little pump spray bottles
>> and I applied the oil as instructed. I pulled the filter out of both
>> cars, installed pleated paper filters, changed the oil and subsequent
>> oil analysis showed that silica readings dropped back to normal. The
>> K&N air filters had only been in the cars a few thousand miles.
>>
>> I learned a huge lesson with this one. Don't trust after market, no
>> matter how well THEY claim THEIR product performs you have to
>> remember that THEY are motivated to sell THEIR PRODUCT.
>
> The only "community" I know about that likes these is the sand rail,
> and they ALWAYS use the oiled bag that fits over the cone filter.
> Without that, they are NOT effective. They actually filter better when
> they are dirty, but then you've lost effective air flow, which is
> usually why those kinds (oiled filters- more porous fibers) of filters are
used.
>
> bob
True, Bob, but what works in sand rails doesn't translate well to other
cars.
Vehicles that operate in areas where the soil is mostly sand and silt
(southwest USA desert, Baja peninsula, etc.) don't do well with paper
filters. Caliche dust and other fine particulates clog paper filters to the
point where airflow is too restricted to run at all.
In this environment, two types of filtration systems are common, simply
because they will get you home without changing filters. First are the
K&N-type free-flowing cotton gauze filters, with or without an oil-soaked
foam pre-filter. Second are antique oil-bath filters that don't work well
(or at all) with modern emissions systems. Both of these systems filter
MOST of the particulates from the incoming air.
Many would argue that the oil-bath filter works as well or better than
modern paper filters, at least up the point where the oil's capacity to
attract more dirt is exceeded. Most types of off-highway heavy equipment in
this environment have multiple filtration systems in series, including
centrifugal separators that remove heavy particles from the intake charge
before it gets to any type of flow-through filter media.
For truly remote travel, where the likelihood of finding a replacement
filter is near zero, and the consequences of a non-running engine are dire,
I would choose the oil-bath filter every time, especially for a diesel or
carbureted gasoline engine. For goofing around in the sand, maybe the oiled
gauze is less messy and doesn't interfere (as much) with sensitive airflow
sensor components, but the trade-off is reduced engine longevity. For the
other 99% of travel, a quality paper filter does an outstanding job. I
carry at least one spare everywhere I go.
Mike
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