Toilet Paper Oil Filter (was Re: [Farmall] Super M Oil

[Andy Wander]

Near as I can tell from studying the manuals and all, the oil filter on
a Cub(not sure about other Farmalls) works in this fashion-that is,
there is an alternate path for the oil, and only some of it goes through
the filter. If the filter gets plugged up completely, you will still
have oil flow.

Makes me wonder just how effective the filter is....

Maybe I'm wrong about this, but from studying the diagrams, it sure
looks like I'm right()to me at least!)


Andy Wander
Verrex Corporation

Date: Sat, 24 Dec 2005 09:45:48 -0500
From: "Steve Offiler" <soffiler at myeastern.com>
Subject: Toilet Paper Oil Filter (was Re: [Farmall] Super M Oil
	Filter)
To: "Farmall/IHC mailing list" <farmall at lists.antique-tractor.com>
Cc: crest25 at sbcglobal.net
Message-ID: <004301c60898$c1ca9c50$27cdd442 at cx2454822a>
Content-Type: text/plain; format=flowed; charset="iso-8859-1";
	reply-type=original

I give Ed a lot of credit for his careful handling of the commercial 
disclaimers.

Personally, having only ever heard of the TP oil filter in the
notoriously 
chintzy JC Whitney catalog of 25-ish years ago, I had a generally
negative 
default opinion from the outset.

To my surprise, a Google search turned up military specification
documents 
referencing bypass oil filtration and toilet paper cartridges.  Maybe
there *is* 
some legitimacy here...?

Correct me if I'm wrong:  I understand that the factory "full-flow" type
filter 
is designed for high flow and low pressure drop, and therefore has
relatively 
large pores in the filtration media.  The TP filter does not replace the
factory 
filter but rather is run in addition to the factory filter.  The TP
filter has 
effectively very small pores and the downside is a much higher pressure
drop and 
reduced flow rate.  Therefore, full flow cannot be run through the TP
filter or 
the engine would starve for oil.  Instead, a fraction of the total oil
flow is 
bypassed and run thru the TP filter where it is cleaned more thoroughly
because 
the filter media has much smaller pores and traps smaller particulate.
This oil 
mixes back with the bulk of the oil, but over time, an averaging effect
takes 
place and all of the oil at some point passes thru the TP filter.  OK so
far?

Questions that arise in my mind:

- A guiding principle in engineering is that everything always takes the
path of 
least resistance.  Since the TP filter is such a heavy restriction,
exactly what 
is the relative flow rate between the oil passing thru the TP filter vs
the 
amount that bypasses?  I would think the flow differences would be quite
large, 
and effectively a tiny fraction of oil is actually being filtered in the
TP 
filter at any given time.

- Claims are made that oil never needs to be changed.  This concerns me.
There 
is far more happening in the oil than merely loading up with microscopic

particulate.  For one thing, acids tend to form, due to combustion
byproducts 
blowing past the rings.  These acids probably won't touch cast iron, but
I'd be 
quite concerned about acidity (over time) damaging bearing shells.  For
another 
thing, oil does in fact "wear out".  Long-chain hydrocarbons break down
over 
time, resulting in what the TV ads call "viscosity breakdown".

- Laboratory oil analysis is quite common these days, and readily
available. 
Has an oil sample ever been tested from a vehicle run for an extended
period of 
time on the TP filter with NO oil changes?  Aside from basic data
indicating the 
condition of the used oil from a lubrication standpoint, this would also
turn up 
evidence of metals such as copper that are being broken down by acids,
not to 
mention stray substances arising from a breakdown of the TP itself.

I'm not criticising Ed.  I am genuinely curious.


Best regards and Happy Holidays to all,
Steve O.
Sterling, CT


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