Fan bearing lubricant was Re: WD-40 (again)

drlegendre . drlegendre at
Tue Apr 19 22:18:38 CDT 2016

Hey, I'm always ready to learn..

One 'trick' I was taught, was to put a quart of ATF into an auto engine
that was down a quart of oil, and ready for a change. Claim was that it had
superior detergent / surfactant qualities, and would clean things up for
the change. You were supposed to run it for 15-20 minutes or whatever, then
drain the pan.

I never tried it. Also had heard similar 'tricks' that involved adding
diesel fuel to the crankcase prior to oil change. Never tried that one,

I suspect a lot of these hacks originated in the days prior to detergent
oils, when it was understood that sludge would build up inside the motor
without intervention. Same thing with old (30s-50s) motor bikes, where one
was warned off of ever using a detergent oil - as opposed to 30W-50W oils -
as it might break loose all the sludge and plug up the oil system, starving
the bearing surfaces.

Heck if I know.

On Tue, Apr 19, 2016 at 10:00 PM, Jon Elson <elson at> wrote:

> On 04/19/2016 08:29 PM, drlegendre . wrote:
>> ATF.. ATF?!?!? Heresy, heresy!!
>> Not.
>> I suppose it depends what we're talking about, Type F or the various
>> grades
>> of Dexron. But that's what I have in my pump oiler can. Per my
>> understanding, it's essentially a highly-refined 20W oil with a series of
>> additives that allow it to serve double-duty as the hydraulic working
>> fluid
>> in torque converters and automatic transmission clutches.
>> Not so sure about that, but maybe it is all in the additives.  it seems
> like typical ATF is a LOT thinner than 20W oil.  Also, it is pretty well
> known that if you put a complete fill of ATF into an engine crankcase, the
> rings will last about 10 miles before the compression goes to zero.
> If you put engine oil in the transmission, then the clutches will slip.
> Jon

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