Date: Sun, 4 Dec 2011 13:36:24 -0500
Reply-To: Michael Snow <slowmachine82@GMAIL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Michael Snow <slowmachine82@GMAIL.COM>
Subject: Re: Oil recommendations simplified
In-Reply-To: <B5FFE4DF-EDF6-4F79-BECB-E64BC35B2B91@gmail.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
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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